The cost, in dollars, of producing x belts is given by C(x) = 644 +20x-0.072x Find the rate at which average cost is changing when 400 belts have been produced. When 400 belts have been produced, the average cost is changing at (Round to four decimal places as needed. Do not include the $ symbol in y for each additional belt. dollars per belt belts per dollar 8 9 The revenue, in dollars, from the sale of x belts is given by R(x)=43x Find the rate at which average revenue is changing when 996 belts have been produced and sold. When 996 belts have been produced and sold, the average revenue is changing at additional belt (Round to four decimal places as needed. Do not include the $ symbol in your answer.) for each dollars per belt belts per dollar The gross domestic product (in billions of dollars) can be approximated by P(t)=568 +1(36106-102), where t is the number of years since 1960 a) Find P'(t) b) Find P'(41) c) in words, explain what P'(41) represents a) Find P'(t). P'(t) = GOOOD