One night a certain hotel rented 3/4 of its rooms. including 2/3 of their air conditioned rooms. if 3/5 of its rooms were air conditioned, what percent of the rooms that were not rented were air conditioned?
Choose the correct choice from the following: A) 20 B) 33 1 / 3 C) 35 D) 40 E) 80

Rationale: consider total # of rooms to be 100 ; as 3 / 5 of the rooms are air conditioned then # of rooms that are air conditioned is 3 / 5 * 100 = 60 ; 3 / 4 rooms were rented - - > 1 / 4 * 100 = 25 were not rented ; 2 / 3 of air conditioned rooms were rented - - > 1 / 3 * 60 = 20 air conditioned room were not rented ; 20 / 25 = 4 / 5 = 80 % . answer : e .
Answer: E