A company makes computers and phones. Computers use 10 machine hours per unit. Phones use 4 machine hours per unit. Per unit variable costs and selling prices follow. Computer Sales price per unit Variable costs per unit $ 1,620 740 Phone $ 864 332 a) For each product, calculate contribution margin per unit. b) For each product, calculate the contribution margin per machine hour. Computer Phone (a) Contribution margin per unit (b) Contribution margin per machine hour