5. Ross Corporation produces a single product. The company has direct materials costs of S8 per uni direct labor costs of $6 per unit, and manufacturing overhead of $10 per unit. Sixty percent of the manufacturing overhead is for fixed costs. In addition, variable selling and administra $2 per unit, and fixed selling and administrative expenses are $3 per unit at the Assume that direct labor is a variable cost. ive expens current activity L Under variable costing, the unit product cost is: a. $24 per unit b. $20 per unit c. $18 per unit d. $21 per unit