Steve can paint a room three times as fast as Billy. When they work together, Steve and Billy can paint a large room in 4 hours. How many hours would it take Billy to paint it by himself?
If Steve does 3 times the work, we can conclude that he did 3/4 of the job. Billy did 1/4 of the job in 4 hours. We only painted 1/4 of the room in 4 hours.
That means it would take him 16 hours to complete one room. 4*4= 16.
It would take him 16 hours to paint a large room by himself.
