please do it as fast as possible

A motel has 70 rooms as follows: 40% singles at $75 per night 35% doubles at $90 per night 25% triples at $100 per night. The motel has annual fixed costs of $620,000and variable cost averages $24.5 per room occupied. How many rooms should they sell in a year to achieve annual operating income of $682,000? O a. 10,000 O b. 21,000 Oc. 15,000 O d. 12,000