The Apex Television Company has to decide on the number of 60- and 42-inch sets to be produced at one of its factories. Market research indicates that at most 40 of the 60-inch sets and 10 of the 42-inch sets can be sold per month. The maximum number of workhours available is 500 per month. A 60-inch set requires 20 work-hours and a 42-inch set requires 10 work-hours. Each 60-inch set sold produces a profit of $120 and each 42-inch set produces a profit of $80. A wholesaler has agreed to purchase all the television sets produced if the numbers do not exceed the maxima indicated by the market research. Formulate a linear programming model for this problem and find the maximum profit of the company.