15. Price is $10 per unit. At current sales volume, cost of goods sold (COGS) is $7 per unit and selling. general, and administrative (SG&A) costs are $5 per unit. Variable costs are $4 per unit. Total fixed costs are unknown. How much will the profit change in the short term if we sell 10 more units? Assume that the new volume is in the relevant range. A Jucrease by $20 B. increase by $30 Cincrease by $10 b. increase by $50 E. increase by $60