申論題

3. (10%) IB company produces x units of commodity A and y units of commodity B. All the units can be sold for p = 20 - 5x dollars per unit of A and q = 4 - 2y dollars per unit of B. The cost (in dollars) of producing these units is given by the joint-cost function C(x,y) = 2xy + 4. What should x and y be to maximize profit?