Case 21.2 Total fixed costs Sale price per unit Variable costs per unit $15.000 $23 $15 Refer to Case 21.2. Assuming 10.000 units are sold, what is the contribution margin? 77) Refer to Case 21.2. If sales revenue per unit increases to S25 and 10.000 units are sold, what is the contribution margin? 78) 79) Refer to Case 21.2. If sales revenue per unit decreases to $18 and 15,000 units are sold, what is the operating income or loss