a woman swims downstream 45 km and upstream 15 km taking 3 hours each time , what is the speed of the woman in still water ?
45 - - - 3 ds = 15 ? - - - - 1 15 - - - - 3 us = 5 ? - - - - 1 m = ? m = ( 15 + 5 ) / 2 = 10 answer : a
divide(add(divide(45, 3), divide(15, 3)), const_2)