The following is Anna Corporation's contribution format income statement for last month: Sales Less: variable expenses Contribution margin Less: fixed expenses $1.200.000 800.000 400,000 Operating income 300.000 $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? b) What is the company's break-even in units? c) If sales increase by 100 units, by how much should operating income increase? d) How many units would the company have to sell to attain target operating income of $125,000