A. What is the variable cost per unit? B. What is the total fixed cost? C. What is the contribution margin per unit? Sales ($100 per unit) Less: Cost of goods sold ($64 per unit) Gross Margin: Less: operating expenses: Salaries $1,600 Advertising 800 Shipping ($4 per unit) 400 Operating Income $10,000 6,400 $3,600 2,800 $ 800