英文数学题☆HELP★~~~~~~~~~~~（还会加分!）
A ship sails out and home(往返）between places A and B.From A to B,it is fair current,From B to A it is reverse current .if we know the speed of this ship in still water is 20km/h.and it takes this ship 6h to sallfrom A to B,however, from B to A this ship takes 1.5times as long as the time from A to B.Can you know the flowing water speed?
Thank you !
有翻译（+5分）
有过程（+10分）