Maximizing profit the weekly demand for dvds manufactured

Question

Question: MAXIMIZING PROFIT The weekly demand for DVDs manufactured by Herald Media Corporation is given by

p = 0.0005x² + 60

Where p denotes the unit price in dollars and x denotes the quantity demanded. The weekly total cost function associated with producing these discs is given by

C(x) = -0.001x² + 18x + 4000

Where C(x) denotes the total cost (in dollars) incurred in pressing x discs. Find the production level that will yield a maximum profit for the manufacturer.