calculate how long it will take a swimmer to swim a distance of 12 km against the current of a river which flows at 1.2 km / hr , given that he can swim in still water at 5 km / h
"swim in still water at = 5 speed of river = 1.2 us = 5 - 1.2 = 3.8 distance = 12 t = 12 / 3.8 = 3.16 answer : b"
divide(12, subtract(5, 1.2))