Problem 12-21 (Algo) Prepare a contribution margin format income statement; answer what-if questions LO 12-7,12-8, 12-9 Shown here is an income statement in the traditional format for a firm with a sales volume of 7,700 units. Cost formulas also are shown: Required: a. Prepare an income statement in the contribution margin format. b. Calculate the contribution margin per unit and the contribution margin ratio. c. Calculate the firm's operating income (or loss) if the volume changed from 7,700 units to 1. 11,550 units. 2. 3,850 units. d. Refer to your answer to part a for total revenues of $34,100. Calculate the firm's operating income (or loss) if unit selling price and variable expenses per unit do not change and total revenues 1. Increase by $13,500. 2. Decrease by $3,500