A shop sells two competing brands of socks, Levis and Gap. Each pair of socks is obtained at a cost of 6 dollars per pair. The manager estimates that if he sells the Levis socks for x dollars per pair and the Gap socks for y dollars per pair, then consumers will buy 21 − 5/2x + y pairs of Levis socks and 1 + 3x − 5/2y pairs of Gap socks. How should the manager set the prices so that the profit will be maximized? Round your answers to the nearest cent.