What is the unit product cost using variable costing?

a. $50 per unit

b. $55 per unit

c. $70 per unit

d. $90 per unit 

Donovan Company incurred the following costs while producing 500 units: direct materials, $10 per unit; direct labor, $25 per unit; variable manufacturing overhead, $15 per unit; total fixed manufacturing overhead costs, $10,000; variable selling and administrative costs, $5 per unit; total fixed selling and administrative costs, $7,500.
There are no beginning inventories.