¶ 1 We hold the tax exemption afforded State-owned property found in OKLA CONST, art. 10, § 6 did not have the effect of extinguishing all Oklahoma County ad var lorem real estate taxes assessed and owing against certain property when appellee, Oklahoma Industrial Finance Authority (OIFA), a State agency, acquired the property. In place of a sale of the property, the Legislature intended 68 O.S.1991, § 2940 to act as the mechanism to insure that all valid ad valorem real estate taxes previously assessed or that would become due prior to OIFA’s acquisition of the property are paid. Normally, § 2940 provides such taxes should be paid by deducting them from the purchase price paid to the private seller for remittance to the County — which was not done in this case. In that taxes required to be paid to County under § 2940 when OIFA purchased the property have not been paid and the Legislature intended § 2940 to be the substitute remedy to sale of the property for collection'of the taxes, the appellants, Oklahoma County Treasurer and Board of Commissioners (County) may sue OIFA in a civil action to recover the taxes if they are not paid.
PARTI. STANDARD OF REVIEW.
¶ 2 The trial court granted summary judgment in favor of OIFA and against County. Thus, the standard for appellate review is that applied to a trial court’s grant of summary judgment which was set out in Carmichael v. Beller, 1996 OK 48, 914 P.2d 1051, as follows:
Athough a trial court in making a decision on whether summary judgment is appropriate considers factual matters, the ultimate decision turns on purely legal determinations, i.e. whether one party is entitled to judgment as a matter of law because there are no material disputed factual questions. Therefore, as the decision involves purely legal determinations, the appellate standard of review of a trial court’s grant of summary judgment is de novo. [This Court], like the trial court, will examine the pleadings and evidentia-ry materials submitted by the parties to determine if there is a genuine issue of material fact. Further, all inferences and conclusions to be drawn from the eviden-tiary materials must be viewed in the light most favorable to the non-moving party, (citations omitted)
Id. at 1058.
PART II. FACTS AND PROCEDURAL BACKGROUND.
¶ 3 OIFA has authority to make loans and secure them by mortgages. The autho*628rization emanates from OKLA. CONST, art. 10, § 33A and is vitalized through the Oklahoma Industrial Finance Authority Act, 74 O.S.1991, § 851 et seq., as amended. OIFA’s purpose is to aid and assist Oklahoma’s industrial development and provide additional employment and payrolls in the State. 74 O.S.1991, § 852. OIFA is authorized to take title by foreclosure to any industrial development project where the acquisition is necessary to protect a loan made by it and may sell, transfer and convey any such project to a responsible buyer. 74 O.S.1991, § 855(o). Further, to minimize financial losses and sustain employment, if sale, transfer or conveyance cannot be accomplished with reasonable promptness, OIFA may lease a project acquired through foreclosure to a responsible tenant or tenants. Id.
¶ 4 In 1988 B & B Wholesale Meat Company, Inc. (B & B) was loaned $525,000.00 from OIFA and $75,000.00 from First American Bank and Trust Company of Purcell (bank). Partly securing the loans was a parity real estate mortgage in which OIFA had an interest of 87.5% and bank, 12.5%.1 B & B defaulted on the loans and bank brought a foreclosure suit, in which OIFA and County were made defendants. OIFA cross-claimed against B & B seeking foreclosure and against County, claiming the superiority of its lien. By a counter/cross-claim, County asserted a superior lien on the property by virtue of delinquent ad valorem real estate taxes for the years 1985 through 1990, as well as liens which might attach during the pendency of the foreclosure suit.2 In reply to County’s counterclaim, bank admitted County’s ad valorem real estate tax liens were superior to its mortgage lien.
¶ 5 OIFA and bank moved for summary judgment; In August 1991 the trial court entered a partial judgment deciding B & B had defaulted on the loans, the amounts owed to OIFA and bank by B & B were determined, and the property was ordered sold.3 The judgment reserved for future consideration County’s claim for taxes. A sheriffs sale was held, which was confirmed by the trial court in February 1992. The purchasers at the sheriffs sale were OIFA and bank who bought the property for $35,-000.00. A sheriffs deed was issued to OIFA and bank as tenants in common in their parity mortgage percentages — i.e. undivided interests of 87.5% and 12.5%, respectively. The sheriffs sale proceeds were insufficient to satisfy OIFA’s mortgage lien against the property. A $35,000.00 credit was given against OIFA’s and bank’s earlier judgment.
¶ 6 Before the trial court finally decided all issues concerning County’s tax lien(s) or claim for past-due taxes, in August 1995 bank sold its interest to OIFA by quitclaim deed reflecting OIFA paid bank $1,000.00. OIFA then moved for summary judgment in rem, essentially asserting that upon its acquisition, the property became tax exempt and any County ad valorem real estate tax lien existing against the property was extinguished. Athough recognizing it could not sell State-owned property to recover past-due real estate taxes arising while the property was previously privately owned, County cross-moved for summary judgment asserting § 2940 gave it an' in personam cause of action against OIFA for a money judgment for all delinquent real estate taxes through August 1995. At the time of filing its cross-motion for summary judgment County submitted an affidavit from a Deputy Treasurer *629for Oklahoma County that $12,613.57 in delinquent taxes, penalties and interest was due and owing for ad valorem real estate taxes. The affidavit also reflects that despite the tax delinquency, the property was never sold in a tax certificate sale or a tax resale.
¶ 7 The trial judge granted judgment in rem to OIFA. He held the property became tax exempt when OIFA acquired it and all County ad valorem real estate taxes assessed and owing against the property while privately owned were extinguished. He also found § 2940 was inapplicable and prohibited County from attempting to collect the taxes from OIFA, its successors or assigns.
¶8 County appealed and the Court of Civil Appeals (COCA), disagreeing with part of the trial judge’s decision, reversed and remanded for further proceedings. County sought certiorari which we previously granted. We now vacate the COCA memorandum opinion, reverse the trial court judgment and remand for further proceedings consistent with this opinion.
PART III. OKLA. CONST. ART. 10, § 6 DID NOT EXTINGUISH VALID OKLAHOMA COUNTY AD VALOREM REAL ESTATE TAXES EITHER PREVIOUSLY ASSESSED OR THAT WOULD HAVE BECOME DUE FOR THE PERIOD THE PROPERTY WAS PRIVATELY OWNED PRIOR TO OIFA’S ACQUISITION.
¶ 9 We first note it is unnecessary to decide in this case whether OKLA. CONST, art. 10, § 6 would in all situations preclude sale of State-owned property as a collection mechanism for the recovery of ad valorem real estate taxes delinquent at the time of State acquisition. Nor must we decide the current status of County’s claimed lien(s) on the real property involved in this ease. Two reasons counsel against the necessity for decisions on these matters. One, County essentially concedes it may not sell the involved property as a method to recover the taxes claimed to be due. Two, as we will set out in Part IV, infra, it is our view, the Legislature intended 68 O.S.1991, § 2940 to act as the substitute remedy — to sale of the property— for collection of validly owing ad valorem real estate taxes arising while the property is in private ownership, but remain unpaid at the time of State acquisition. With these matters understood, we turn to our review of the trial court’s judgment.
¶ 10 In interpreting an Oklahoma constitutional provision our goal is to give effect to the intent of its framers and the people adopting it. Draper v. State, 1980 OK 117, 621 P.2d 1142, 1145. To determine this intent we look to the instrument itself and when the text of a constitutional provision is unambiguous, the courts, in construing it, are not at liberty to search for meaning beyond the instrument. Id. at 1145-1146. The tax exemption for State-owned property found in OKLA. CONST. art. 10, § 6 provides in pertinent part as follows: “[A]ll property of this state, and of counties and of municipalities of this state ... shall be exempt from taxation....”4
¶ 11 The unambiguous language of § 6 concerns itself only with granting a tax exemption to property of the State once the property is acquired by the State — i.e. the provision is plainly prospective in nature and does not purport to reach the issue of how to handle previously assessed taxes or those that may be due for the period of time the property remained in private ownership prior to the State’s acquisition.5 Confusion has arisen on this point, however, mainly beginning with this Court’s decision in State ex rel. Commissioners of Land Office v. Galyon, 154 Okla. 204, 7 P.2d 484 (1932).
*630¶ 12In Galyon, this Court held that real estate acquired by the State in its sovereign capacity is thereupon absolved and freed of further liability for the taxes previously assessed against it while in private ownership and a county treasurer is thereafter without legal authority to sell the property for such past-due taxes. 7 P.2d at 484, Syllabus One. Part of the rationale contained in Galyon for this proposition appeared to be the tax exemption afforded State-owned property contained in OKLA. CONST. art. 10, § 6.
¶ 13 The situation in Galyon was that the Commissioners of the Land Office had loaned a private land owner money from the school land trust fund and secured the loan with a mortgage. 7 P.2d at 485. The mortgage was foreclosed and the Commissioners purchased the land at sheriffs sale. Id. The Commissioners then sued to permanently enjoin a county treasurer from advertising for sale and selling the involved property for delinquent taxes arising while it was still in private ownership. Id. This Court ruled the Commissioners were entitled to a permanent injunction as requested. Id. at 486.
¶ 14 The Commissioners of the Land Office, a constitutionally established State agency, have charge of the sale, rental, disposal and management of the school lands and other public lands of the State, and of the funds and proceeds derived therefrom, under rules and regulations prescribed by the Legislature. OKLA. CONST. art. 6, § 32. As part of this charge, the Commissioners are given the responsibility for the investment of the permanent common school and other educational funds. OKLA. CONST. art. 11, § 6(B) (1997 O.S.Supp). Strict constitutionally based restrictions are placed on the use of these funds. The restrictions include: that the income from the permanent school fund shall be used for the maintenance of the State’s common schools, that the principal shall be deemed a trust fund that shall forever remain inviolate and that the fund shall never be diminished. OKLA. CONST. art. 11, § 2. Further, no portion of the permanent school fund may be diverted for any other use or purpose. Id.6 This Court has also recognized the State has an irrevocable duty, as Trustee, to manage the trust estate for the exclusive benefit of the beneficiaries and return full value from the use and disposition of the trust property. Oklahoma Education Association, Inc. v. Nigh, 1982 OK 22, 642 P.2d 230, 235-236.
¶ 15 In our view, Galyon should be read as a recognition that allowing the sale of lands acquired by the Commissioners in the course of their constitutional duties to pay for previously assessed taxes, would be inconsistent with the protection afforded school land trust funds in the above-referenced constitutional provisions.7 Galyon cannot, however, be taken to mean that the tax exemption afforded State-owned property found in OKLA. CONST. art. 10, § 6 automatically cancels all outstanding ad valorem real estate taxes validly assessed prior to acquisition by a State agency like OIFA, as the trial court appears to have ruled. Nor may Ga-lyon be read to mean the Legislature is prohibited by the force of § 6 from mandating that such previously assessed taxes are required to be paid when a State agency like OIFA acquires real property, as it has done in this case.
¶ 16 Generally, the Legislature has authority to require payment of taxes assessed against real estate while privately owned, but which remain unpaid when the State acquires the property for some legitimate governmental purpose. This legislative authority was expressly recognized in Board of Commissioners of Marshall County v. Shaw, 199 Okla. 66, 182 P.2d 507 (1947) where this Court upheld, over various Oklahoma constitutional challenges, a law pro*631mulgated by the Oklahoma Legislature that reimbursed two counties for taxes lost by virtue of the establishment and liquidation of a State prison farm. The taxes reimbursed included those which were assessed while the property was privately owned, but which remained unpaid at the time the State initially acquired the real estate. Id. at 509.
¶ 17 The trial court, therefore, erred in granting OIFA a judgment to the effect that when OIFA acquired the property all County ad valorem real estate taxes assessed and owing against the property while privately owned were extinguished.
PART IV. 68 O.S.1991, § 2940 IS PLAINLY APPLICABLE TO OIFA’S ACQUISITION OF THIS PROPERTY AND REQUIRES PAYMENT OF AD VALOREM REAL ESTATE TAXES EITHER PREVIOUSLY ASSESSED OR THAT WOULD HAVE BECOME DUE FOR THE PERIOD THE PROPERTY WAS PRIVATELY OWNED PRIOR TO OIFA’S ACQUISITION.
¶ 18 Although recognising delinquent taxes arising while the property was previously in private ownership cannot now be collected in the normal manner by sale of the real estate because it is owned by the State, County asserts the Legislature granted it an in personam action against the State (here represented by OIFA — a State agency) in § 2940 to recover a money judgment for the past-due taxes. The trial court determined § 2940 was inapplicable. We disagree. Section 2940 provides:
Whenever the United States, the state, or a city, town, county, school district, or any other political subdivision, including, but not limited to, a turnpike authority, municipal trust, water or conservation district, flood control district, levee or waterway improvement district, urban renewal authority, public housing authority, or any other authority authorized by law, state or federal, acquires title to any real property for a governmental purpose between January 1 and October 1 of the tax year, such property shall be relieved of ad valorem tax for the remaining months of the year beginning with the first of the month next succeeding the date its acquisition for public purposes becomes a matter of public record, if the deed thereto was recorded prior to October 1; provided, however, that all taxes assessed against such property prior to its acquisition shall be paid in full and there be paid a sum equal to one-twelfth ⅝) times the number of months that the property remained in private ownership of an amount estimated by the county treasurer of the county wherein the real property lies to be substantially equal to the amount of tax which would have been or will become due and payable for the year had the real property not been acquired for public purposes. In estimating the amount of taxes which would have been or will become due and payable for the tax year had the real property not been acquired for public purposes the county treasurer shall use as a basis the current assessment and the tax rate for the preceding year, unless the tax for the current year shall be by then determined and set, in which event he shall use as basis the new assessment and rate. The public agency acquiring the property shall deduct the amount of such taxes from the purchase price payable to the private owner and remit the same to the county treasurer in satisfaction of such taxes. The county treasurer of any county is hereby authorized upon order of the board of tax roll corrections to cancel of record all taxes assessed against such property for the year of its acquisition when the deed thereto was recorded prior to October 1 and the aforesaid estimated amount of the tax for the months that the property was in private ownership is paid, which order shall be issued upon application of the acquiring authority.
¶ 19 Of course, the fundamental rule of statutory construction is to ascertain and give effect to legislative intent. We are also guided by 25 O.S.1991, § 1 which generally requires that words used in a statute are to be understood in their ordinary sense unless a contrary intention plainly appears. Further, where the Legislature has clearly expressed its intent, the use of additional rules of construction are unnecessary and a statute *632will be applied as written. Fuller v. Odom, 1987 OK 64, 741 P.2d 449, 452-453.
¶20 The plain language of § 2940 provides, upon acquisition by the State for a governmental purpose, the real estate shall be relieved of future ad valorem taxation. However, the statute also unequivocally expresses legislative intent that taxes assessed prior to a covered acquisition “shall be paid in full” and essentially that a proportional share of the current (i.e. acquisition) year taxes that would have been or will become due for the period of time the property remained in private ownership prior to the governmental agency’s acquisition, shall also be paid. The statute further provides that the public agency acquiring the property shall deduct the taxes mandated to be paid from the purchase price payable to the private owner and remit them to the county treasurer. As far as this record shows, no taxes were deducted or remitted to the County when OIFA purchased the property, partly at sheriffs sale and partly from the bank.
¶ 21 As we read § 2940, the involved acquisition by OIFA was unmistakably intended by the Legislature to fall within the statute’s ambit because OIFA’s acquisition was clearly one by a State instrumentality for a governmental or public purpose. OIFA is defined as a body corporate and politic, constituting a public corporation and governmental instrumentality of the State of Oklahoma. 74 O.S.1991, § 854(A). It is expressly empowered, in the sphere in which it acts, to exercise public powers of the State. 74 O.S.1991, § 855. Further, there can be no doubt that in acquiring the real estate involved in this ease, OIFA was acquiring it for a governmental or public purpose, to wit: carrying out its mandate to aid and assist Oklahoma’s industrial development. See Burkhardt v. City of Enid, 1989 OK 45, 771 P.2d 608 (economic development is a legitimate public purpose within the meaning of OKLA. CONST. art. 10, § 14 which restricts the use of public funds to expenditures for a public purpose). The Legislature itself has recognized that OIFA’s loan of funds for industrial development is geared toward a public purpose. 74 O.S.1991, § 859. Clearly then, contrary to the trial court’s determination of inapplicability, § 2940 plainly applies to OIFA’s acquisition of the involved property.
¶ 22 Normally, when taxes due and owing on real property are not paid in a timely manner and become delinquent, the provisions of the Ad Valorem Tax Code, 68 O.S. 1991, § 2801 et seq., as amended, provide a detailed statutory scheme for their recovery. If the taxes are not paid, implementation of the Tax Code requires public offering of the .property for sale to recoup the taxes. 68 O.S.1991, § 3101 et seq., as amended. Under the Tax Code, one of the potential ultimate outcomes of the collection mechanisms for delinquent taxes is divestment of an owner’s right, title and interest in the land, and a vesting in a resale tax deed purchaser an absolute and perfect title in fee simple to the real estate. Dunlap v. Mayer, 1959 OK 125, 341 P.2d 258 Syllabus by the Court; 68 O.S.Supp.1997, § 3131(a).
¶23 In our opinion, § 2940 was plainly intended by the Legislature to act as the substitute mechanism for enforcement of the payment of due and owing ad valorem taxes in the situation where the State, through one of its agencies, acquires property for a governmental purpose upon which previously assessed taxes are unpaid or that would become due prior to the State’s acquisition. In other words, the obvious intent of § 2940 was that it act as a substitute remedy for the normal, method of collection of ad valorem taxes contained in the Ad Valorem Tax Code, a method which ultimately could lead to divestment of the property owner’s title to the real property. Accordingly, in that taxes required to be paid to County under § 2940 when OIFA purchased the property have not been paid, County may sue OIFA in a civil action to recover them if they are not paid8 *633and the trial court erred in enjoining County from attempting to collect such taxes from OIFA.9
PARTY. CONCLUSION.
¶24 The trial court erred in granting OIFA a judgment to the effect that when OIFA acquired the property all County ad valorem real estate taxes assessed and owing against the property while privately owned were extinguished. OKLA. CONST. art. 10, § 6 does not mandate such an effect, but only applies to grant a tax exemption to State-owned property once it is acquired by the State. Further, 68 O.S.1991, § 2940 is unmistakably applicable to OIFA’s acquisition of the real estate involved here. Section 2940 requires that ad valorem real estate taxes assessed while the property was previously in private ownership and such taxes which would have become due in the year of acquisition for that period of time the property remained in private ownership prior to OIFA’s acquisition, must be paid in full. Section 2940 was intended to act as the substitute mechanism for the normal method of collection of ad valorem taxes contained in the Ad Valorem Tax Code (i.e. sale of the property) in the situation where the State, through one of its agencies acquires property for a governmental purpose upon which previously assessed taxes are unpaid or that would become due prior to the State’s acquisition. In that such ad valorem taxes have not been paid as required by § 2940 in the situation presented here, County may sue OIFA in a civil action to collect them if they are not paid.
¶ 25 The Court of Civil Appeals’ memorandum Opinion is VACATED, the trial court judgment is REVERSED AND THE MATTER IS REMANDED TO THE TRIAL COURT FOR FURTHER PROCEEDINGS CONSISTENT WITH THIS OPINION.
¶ 26 HODGES, LAVENDER, SIMMS, HARGRAVE and WATT, JJ., concur. ¶ 27 KAUGER, C.J., concurs in result. ¶ 28 OPALA and WILSON, JJ., concur in part; dissent in part. ¶ 29 SUMMERS, V.C.J., disqualified..In actuality, the record indicates OIFA made an industrial development loan to the Oklahoma County Finance Authority (OCFA), who in turn loaned the money to B & B and that OCFA was the original mortgagee, along with bank, in the mortgage. The OCFA’s note and its share in the mortgage were assigned to OIFA. The record also indicates security interests were taken in B & B personal property and certain personal guarantees were obtained to secure repayment. Finally, the record shows bank had other financial dealings with B & B and/or its principals, which are not relevant to our decision.
. County also claimed a lien on the property by virtue of certain unpaid personal business taxes. No issue concerning such taxes is before us in this appeal.
. The August 1991 partial judgment, as it relates to B & B, was only an in rem judgment in regard to the subject property for the amounts due from B & B on the involved notes. No personal judgment against B & B was issued, apparently because B & B had filed for bankruptcy and the automatic stay of the bankruptcy laws had only been lifted as it pertained to the subject property.
. Although OKLA. CONST. art. 10, § 6, has undergone amendment in certain particulars over the years, the express tax exemption for property of the State has existed since the Statehood era. See OKLA. CONST. art. 10, § 6, REV. LAWS OKLA. ANN. (1910). The language quoted in the text currently appears in subsection (a) of art. 10, § 6 of the Oklahoma Constitution. OKLA. CONST. art. 10, § 6 was most recently amended in a way not germane to this proceeding in 1992.
. As to the tax exemption once the property is owned by the State, county or municipality, this Court has recognized the exemption is unconditional and without limitation, and applies without reference to the use the property may be put. State ex rel. City of Tulsa v. Mayes, 174 Okla. 286, 51 P.2d 266 (1935).
. OKLA. CONST. art. 11, § 5 contains similar restrictions on certain other funds constitutionally designated for use by certain educational institutions of the State.
. In fact, in order to safeguard the school land trust funds, the Legislature itself passed a statute in 1935 providing for the cancellation of previously assessed taxes on land acquired by the Commissioners of the Land Office. 1935 Okla. Sess.Laws, p. 116-117, § 29; See now 64 O.S. 1991, § 151. In State ex rel. Commissioners of Land Office v. Passmore, 189 Okla. 232, 115 P.2d 120, 121-122 (1941) this Court recognized § 151 was passed to safeguard the school land trust funds.
. We note the Legislature has authorized OIFA to sue and be sued in all courts. 74 O.S.1991, § 855(h).
. OIFA’s reliance on 68 O.S.1991, § 3142, a provision in the Ad Valorem Tax Code, to support its position in this matter is unavailing. Section 3142 provides:
Whenever any lands shall be sold for delinquent taxes under the provisions of this article, upon which any mortgage or other lien exists in favor of the State of Oklahoma, or the Commissioners of the Land Office or any other commission, board or officer having power to loan public funds, or any funds under the control of the state upon real estate security, such tax shall be secondary at all times to the lien of the state, or the Commissioners of the Land Office, or of such commission, board or officer.
First, § 3142 does not apply here because there is no indication in this record the involved real estate was sold for delinquent taxes under the Ad Valorem Tax Code. Second, the primary purpose served by § 3142 is to insure that a State mortgage lien could not be foreclosed or divested in any county tax sale by making clear that an ad valorem tax lien is inferior or secondary to a State mortgage lien. See Goode v. Montgomery, 195 Okla. 63, 155 P.2d 228 (1945); State ex rel. Commissioners of the Land Office v. Passmore, note 7, supra. In other words, any purchaser at a tax sale upon which the State holds a mortgage lien would take subject to the mortgage lien of the State. Section 3142 simply does not control the issue of whether the Legislature, as it has done in 68 O.S.1991, § 2940, may mandate that delinquent ad valorem taxes must be paid when the State acquires real property for a governmental purpose.