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. 1. 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? 2. What is the company's margin of safety percentage? 3. What is the company's degree of operating leverage?