Speed of boat B in still water = xkmph ∴ Speed of boat A in still water = (x−3)kmph Speed of current = ykmph According to the question, x−y+x−3+y = 27 ⇒ 2x = 27+3 = 30 ⇒ x = 15kmph ∴ Speed of boat A in still water = 15−3 = 12kmph ∴ Required ratio = 12 : 15 = 4 : 5