A liquid form of penicillin manufactured by a pharmaceutical firm is sold in bulk at a price of
$200 per unit. If the total production cost (in dollars) for x units is
C(x) = 500,000 + 80x + 0.003x^2
and if the production capacity of the firm is at most 30,000 units in a specfied time, how many
units of penicillin must be manufactured and sold in that time to maximize the profit?