The price p​ (in dollars) and the quantity x sold of a certain product obey the demand equation. ​x=-4p+80 0

(a) Express the revenue R as a function of p. ​(b) What is the revenue if the price is ​$​18?​(c) What price p maximizes​ revenue? What is the maximum​ revenue? The price p that maximizes revenue is The maximum revenue is