In preparation for the upcoming Olympics, Rita's swimming coach requires her to swim a total of 1,500 hours. Rita has already completed 50 hours of backstroke, 9 hours of breaststroke, and 121 hours of butterfly, but she is unhappy with her inconsistency. She has therefore decided to dedicate 220 hours every month practicing freestyle and sidestroke. How many months does Rita have to fulfill her coach’s requirements?
Give me a detailed solution.