7. Suppose the profit P of selling espresso machines at p dollars per machine is given by P(p)= -2p +640p - 20000. The graph of P is shown below. Answer the following questions in complete sentences. (31.1.0) (6-20000) (18031300) (1490) 30 (a) What do the z-intercepts mean in the context of this problem? (b) How much should be charged per machine in order to maximize profit? (c) What is the maximum profit that can be attained? (d) Find and interpret the average change in profit when the price of an espresso machine starts at $160 and increases to $284.90.