The St. Louis Police Officers’ Association, Gary Phelps, and William Gooden (collectively “Association”) appeal from the judgment of the trial court denying their petition for an injunction to prevent the Board of Police Commissioners of the City of St. Louis (“Board”) from reducing the free health insurance benefits of retired police officers that is mandated by statute. The judgment is reversed, and the case is remanded.
I.
Prior to 2006, retired police officers who served in the City of St. Louis Police Department received health coverage without having to pay an insurance premium. In 2006, the Board altered the health insurance plan for retired officers. The new health insurance plan included a basic plan available without payment of a premium and a buy-up plan, which has a $251 monthly premium. The basic plan differed from the former plan by raising annual deductibles from $500 to $2,250, increasing co-payments for office and hospital visits, increasing the coinsurance maximum, and decreasing the coinsurance coverage percentage. The buy-up plan offers retirees the same more extensive coverage as provided to active police officers.1 The difference between the buy-up plan and the plan *528for active officers is that active police officers do not pay premiums.
The Association filed a petition seeking to enjoin the Board from implementing the new health insurance plan. The Association alleged that the new insurance plan was inconsistent with section 84.160.8(3), RSMo Supp.2006, which provides that the Board “shall provide” health insurance to police retirees.2 The Association also alleged that implementation of the Board’s new free insurance plan would unreasonably, arbitrarily, and capriciously deprive police retirees of a vested property right without due process of law in violation of the United States Constitution and the Missouri Constitution and their civil rights under 42 U.S.C. section 1983.
The circuit court issued a preliminary injunction in favor of the Association. At trial, there was expert testimony indicating that the insurance provided to retirees without the payment of a premium offered less coverage at a higher cost than any other group health insurance plan with which the experts were familiar. Following a bench trial, the court entered a judgment denying the Association’s request for a permanent injunction.
This Court concludes that the new policy does not meet the requirements of section 84.160.8(3). Consequently, the judgment is reversed, and the case is remanded so that the trial court may grant the requested relief.
II.
An action for an injunction is an equitable action. Supermarket Merchandising & Supply, Inc. v. Marschuetz, 196 S.W.3d 581, 585 (Mo.App.2006). The trial court’s judgment in a suit seeking equitable relief will be affirmed unless there is no substantial evidence to support it, it is against the weight of the evidence, or it erroneously declares or applies the law. Conseco Finance Servicing Corp. v. Missouri Dept of Revenue, 98 S.W.3d 540, 542 (Mo. banc 2003).
Section 84.160.8(3) provides that “the board of police commissioners shall provide health, medical, and life insurance coverage for retired officers and employees of the police department.” The issue is whether the basic plan and the buy-up plans offered by the Board violate the requirement that the board “shall provide” health insurance coverage for retired officers.
The primary rule of statutory construction is to “ascertain the intent of the legislature from the language used, to give effect to the intent if possible, and to consider the words in their plain and ordinary meaning.” Nelson v. Crane, 187 S.W.3d 868, 869-870 (Mo. banc 2006). Related statutes are relevant in considering the meaning of the statute at issue. Lane v. Lensmeyer, 158 S.W.3d 218, 226 (Mo. banc 2005). Statutes are interpreted to avoid unreasonable or absurd results. Reichert v. Board of Educ. of City of St. Louis, 217 S.W.3d 301, 305 (Mo. banc 2007).
The legislature provides no guidance as to what minimal extent of coverage will satisfy the requirement that the Board “shall provide” insurance. Generally the use of the word “shall” connotes a mandatory duty. Bauer v. Transitional School District of City of St. Louis, 111 S.W.3d 405, 408 (Mo. banc 2003). The word “provide” means “to supply or make available.” Webster’s Ninth New Collegiate Dictionary (1986).3 This language means that *529the Board is under an affirmative obligation to supply health insurance coverage to retirees but does not resolve the issue of the minimal extent of that coverage.4
In determining the minimal extent of coverage required by section 84.160.8(3), related statutes are relevant to further clarify the meaning of a statute. See State v. Withrow, 8 S.W.3d 75, 80 (Mo. banc 1999). The statute most closely related to section 84.160.8(3) is section 84.160.8(1), which states that the Board “shall provide or contract for life insurance coverage and for insurance benefits providing health, medical and disability coverage for officers and employees of the department.” The Board fulfills its statutory obligations under section 84.160.8(1) by providing to active duty officers essentially the same coverage offered in the buy-up plan but without the payment of a monthly premium.
Although section 84.160.8(3) imposes upon the Board nearly the same requirement with respect to retirees, the Board now requires retirees to pay a substantial monthly premium to obtain the same benefit provided to active duty officers without the payment of a premium. The Board does so despite the fact that the retired officers invested their entire career in the police department in consideration for a promise of healthcare in retirement, only to have the Board change course after the officers retired. The promise of healthcare in retirement is a critical benefit given the enhanced risk of injury and disability inherent in policing. The difference in insurance benefits offered to active officers and retirees is not consistent with the nearly identical statutory language governing the Board’s treatment of its active officers and retirees. The Board is statutorily obligated to “provide” health insurance benefits to both its active officers and retirees. In order to avoid unreasonable discrepancies in insurance coverage provided to active duty officers under section 84.160.8(1) and to retirees under section 84.160.8(3), the Board must provide its retirees with substantially the same level of reasonable benefits provided to active duty officers without payment of a premium.
The judgment denying the petition for injunctive relief is reversed,5 and the case is remanded.
PRICE and WOLFF, JJ., concur. BRECKENRIDGE, J., concurs in part and dissents in part in separate opinion filed. STITH, C.J., and RUSSELL, J. concur in opinion of BRECKENRIDGE, J. LIMBAUGH, J., dissents in separate opinion filed.. The following are some of the provisions of basic plan and the buy-up plan:
Basic Plan
Annual Individual Deductible: $ 2,250
Individual Coinsurance Maximum: $ 5,200
Office Visit Co-Pay: $ 30
Emergency Room Co-Pay: $ 50
Medical Program Maximum: Unlimited
3-Tier Co-Pay Prescription Drugs: $ 10/$35/$75
Buy-up Plan
Annual Individual Deductible: $ 0
Individual Coinsurance Maximum: $ 0
Office Visit Co-Pay: $ 15
Emergency Room Co-Pay: $ 50
Medical Program Maximum: Unlimited
3-Tier Co-Pay Prescription Drugs: $ 8/$25/$45
. Section 84.160 has been amended several times since 2001 but the language at issue has not changed since 2000. All further statutory citations, unless noted otherwise, are to RSMo Supp.2006.
. The word "provide” is also defined as “to *529supply what is needed for sustenance or support.” Webster’s Third New International Dictionary (1966).
. This conclusion is further supported by the fact that section 84.160.8(3) provides that the Board "shall provide" insurance coverage for retired officers and, in the very next sentence, states that with respect to spouse and dependents, insurance coverage "shall be made available for purchase....” The phrase "shall provide” is substantially different from the phrase "shall be made available for purchase" and implies that the Board must provide to its retirees insurance coverage without the necessity of paying a premium. Although the basic plan is available without the payment of a premium, the fact remains that the coverage available under the basic plan is substantially less than that under the coverage previously offered to the retirees.
. The result in this case eliminates the need to address the Association’s constitutional arguments.