Mazoon Company sells yachts. During the current year, 100 yachts were sold resulting in $420,000 of sales revenue, $120,000 of variable costs, and $100,000 of fixed costs. The number of yachts that must be sold to achieve $140,000 of operating income is: a. None of the given answers b. 2400 units O c. 90 units O d. 80 units e. 47 units