Suppose that when apples sell for x cents per pound and bakers earn y dollars per hour, the price of apple pies at a certain supermarket chain is

dollars per pie. Suppose also that t months from now, the price of apples will be x = 129 − √8t cents per pound and bakers’ wages will be y = 15.60 + 0.2t dollars per hour. If the supermarket chain can sell Q = 4,184/p pies per week when the price is p dollars per pie, at what rate will the weekly demand Q for pies be changing with respect to time 2 months from now?

p(x, y) 1 -X//2 4