calculate how long it will take a swimmer to swim a distance of 3 km against the current of a river which flows at 1.7 km / hr , given that he can swim in still water at 3 km / h
"swim in still water at = 3 speed of river = 1.7 us = 3 - 1.7 = 1.3 distance = 3 t = 3 / 1.3 = 2.31 answer : a"
divide(3, subtract(3, 1.7))