The profit in dollars from the sale of x expensive watches is P(x) = 0.06x- - 5x + 4x -5100. Find the marginal profit when (a) x = 300, (b) x =2000, (c) x =5000, and (d) x = 10,000. (a) When x = 300, the marginal profit is $ (Round to the nearest integer as needed.) (b) When x = 2000, the marginal profit is $ (Round to the nearest integer as needed.) (c) When x = 5000, the marginal profit is $ . (Round to the nearest integer as needed.) (d) When x = 10,000, the marginal profit is $ (Round to the nearest integer as needed.)