A computer system which uses customer-based business rules that are customized for each customer. These business rules, along with order information, are provided to a linear programming engine. The linear programming engine determines the priority of customer orders based on the business rules and allocates scarce inventory accordingly. In one embodiment, linear programming assigns weights to different factors. Examples of such factors are (1) a promotion activity, (2) a customer priority, (3) the age and delinquency of an order or line item, and (4) the price of the product.