a boy swims downstream 48 km and upstream 12 km taking 6 hours each time ; what is the speed of the current ?
"48 - - - 6 ds = 8 ? - - - - 1 12 - - - - 6 us = 2 ? - - - - 1 s = ? s = ( 8 - 2 ) / 2 = 3 answer : c"
multiply(divide(const_1, const_2), add(divide(48, 6), divide(12, 6)))