A room can be cleaned in 2 hours if rob and Harry work together. Ron could clean it in 3 hours. How long can harry clean it?
Ron = R
Harry = H
1 / 2 - 1 / R = 1 / H
1 / 2 - 1 /3 = 1 / H, solve for H
H = 6 Hours it takes Harry to clean the room by himself.
