a man swims downstream 76 km and upstream 48 km taking 4 hours each time ; what is the speed of the current ?
"explanation : 76 - - - 4 ds = 19 ? - - - - 1 48 - - - - 4 us = 12 ? - - - - 1 s = ? s = ( 19 - 12 ) / 2 = 3.5 answer : option c"
divide(add(divide(48, 4), divide(76, 4)), const_2)