Part A requires 4 hours per unit on a lathe and 3 hours per unit on a milling machine. Part B requires 2 hours per unit on a lathe and 5 hours per unit on a milling machine. 52 hours are available on the lathe and 60 hours are available on the milling machine. If the profit per unit on Part A is $2 and on part B is $4, how many units of each part should be made maximize profit?