A retailer has been selling 400 tablet computers a week at $350 each. The marketing department estimates that an additional 80 tablets will sell each week for every $10 that the price is lowered.(a) Find the demand function.

p(x) =

(b) What should the price be set at in order to maximize revenue? $ (c) If the retailer's weekly cost function is

C(x) = 35,000 + 140x

what price should it choose in order to maximize its profit? $