Subject: mathqa
Question: one night a certain hotel rented 3 / 5 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 ?
Option: 
A: 60 %
B: 50 %
C: 55 %
D: 65 %
Answer: B