The following is Marang manufacturing Company 's contribution format income statement for last month: Sales R1 200 000 Variable expenses 800 000 Contribution margin 400 000 Fixed expenses 300 000 Net operating Income R 100 000 The company has no beginning or ending inventories and produced and sold 20,000 units during the month. Required: a. What is the company's contribution margin ratio? (3) b. What is the company's break-even in units? (5)c. If sales increase by 100