Net Income Planning Nolden Company has charged a selling price of $20 per unit, incurred variable costs of $14 per unit, and total fixed costs of $60,000. What unit sales volume is necessary to earn the following related amounts of net income before income tax? (a) $18,000; (b) $27,000; or (c) equal to 20% of sales revenue. (a) 0 units (b) 0 units (c) 0 units