a man swims downstream 120 km and upstream 50 km taking 5 hours each time ; what is the speed of the current ?
"explanation : 120 - - - 5 ds = 24 ? - - - - 1 50 - - - - 5 us = 10 ? - - - - 1 s = ? s = ( 24 - 10 ) / 2 = 7 answer : option b"
divide(add(divide(50, 5), divide(120, 5)), const_2)