a retailer has determined that the number of tv sets he can sell per week is 7x2x4y5y 2x 7x 5y 4y where x and y represent his weekly expenditures (in dollars) on newspaper and radio advertising, respectively the profit is $300 per sale, less the cost of advertising, so the weekly profit is given by the formula p300(7x2x4y5y)xy find the values of x and y for which the profit is a relative maximum use the secondderivative test to verify that your answer corresponds to a relative maximum