The following is Arkadia Corporation's contribution format income statement for last month:

Sales Less: variable expenses Contribution margin Less: fixed expenses $1,200,000 800,000 400,000 300,000 $100,000 Operating income 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? e) What is the company's margin of safety in dollars? f) What is the company's degree of operating leverage? g) If the tax rate is 30%, how many units must be sold to attain an after tax profit of $84,000?