Required ARequired B Assume that only one product is being sold in each of the four following case situations: Case 1 Case 2 Case 3 Case 4 Units sold 15,000 10,000 6,000 Sales $180,000 $100,000 $300,000 Variable expenses 120,000 70,000 Contribution margin Fixed expenses 50,000 32,000 100,000 Net operating income (loss) $8,000 $12,000 $(10,000) Contribution margin per unit $10 $13