National Business Machines manufactures two models of fax machines: A and B. Each model A costs $90 to make, and each model B costs $140.

National Business Machines manufactures two models of fax machines: A and B. Each model A costs $90 to make, and each model B costs $140. The profits are $28 for each model A and $42 for each model B fax machine. If the total number of fax machines demanded per month does not exceed 2600 and the company has earmarked no more than $500,000/month for manufacturing costs, how many units of each model should National make each month in order to maximize its monthly profit?