Business and Economics 43. Cost and Revenue For a certain product, cost C and revenue R are given as follows, where x is the number of units sold (in hundreds) Cost: C' = x3 + 100Vx + 50 Revenue: 900(x - 5)3 + 25RX = 22,500 (a) Find and interpret the marginal cost dC/dr at x = 5. (b) Find and interpret the marginal revenue dR/dx at x = 5