The total cost​ (in dollars) of manufacturing x auto body frames is ​C(x)=40,000+500x. ​(A) Find the average cost per unit if 200 frames are produced. ​(B) Find the marginal average cost at a production level of 500 units. ​(C) Use the results from parts​ (A) and​ (B) to estimate the average cost per frame if 501 frames are produced.