The following is Arkadia Corporation's contribution format income statement for last month: Sales Variable expenses Contribution margin Fixed expenses Net operating income $1,200,000 800,000 400,000 245,000 $155,000 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 180 units, by how much should net operating income increase? d. How many units would the company have to sell to attain a target profit of $138,000? e. What is the company's margin of safety in dollars? f. What is the company's degree of operating leverage