This article considers an economic system that consists of three types of business entities: a manufacturer, a distributor, and a retailer. Mathematical models that allow the distributor to make informed decisions about the volume of goods purchased from the manufacturer are considered, using the assessment of upcoming retail sales, assuming that the manufacturer's selling price depends on the volume of purchases. Models are built from the standpoint of resolving conflicts between participants in the decision-making process: purchasing managers who strive to have enough inventory and financiers who want to reduce this volume, for example, to increase the liquidity of the organization's assets or reduce storage costs. The constructed models allow the distributor to solve the problem of determining the optimal volume of goods to purchase that will maximize additional profit.