The following is Allison Corporation's contribution format income statement for last month: Sales $800,000 Less: variable expenses 400,000 Contribution margin 400,000 Less: fixed expenses 300,000 Operating income $100,000 The company has no beginning or ending inventories. The company produced and sold 20,000 units last month. How many units would the company have to sell to attain after-tax profits of $72,000, assuming it is subject to a 40% income tax rate? a. 10,400 units. b. 12,000 units. c. 9,440