Suppose that Dent Carr's long-run total cost of repairing s cars per week is c(s)  3s²  75.If the price he receives for repairing a car is $36, then in the long run, how many cars will he fix per week if he maximize profits?

A) 0
B) 12
C) 9
D) 6
E) 18

To maximize profits, Dent Carr will choose the quantity of cars to repair (s) where marginal cost (MC) equals marginal revenue (MR). Given the price per car repair is $36, MR is $36. The long-run total cost function is given as $c(s)=3s^2+75$ . To find MC, we differentiate c(s) with respect to s, which gives $MC=6s$ . Setting MC equal to MR, we have $6s=36$ , solving for s gives $s=6$ . Therefore, to maximize profits, Dent Carr will fix 6 cars per week.