With the following data, how many units must be sold to generate an operating income of $20,000? Fixed expenses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . $40,000 Selling price . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . $50 per unit Contribution margin ratio . . . . . . . . . . . . . . . . . . . . . . . . . 30 percent a. 800. b. 1,000. c. 2,500. d. 3,500. e. 4,000