A, B and C working together can finish a piece of work in 8 hours. A alone can do it in 20 hours and B alone can do It in 24 hours. In how many hours will C atone do the salve work?
A can do a piece of work in 4 hours; B and C together can do it in 3 hours, while A and C together an do it in 2 hours. How long will B alone take to do it?