A motion boat covers a given distance in 6 h moving down stream of a river. It covers the same distance in10 h moving upstream. The time (in hour) it takes to cover the same distance in still water is

Question :A motion boat covers a given distance in 6 h moving down stream of a river. It covers the same distance in10 h moving upstream. The time (in hour) it takes to cover the same distance in still water is