a man swims downstream 48 km and upstream 32 km taking 8 hours each time ; what is the speed of the current ?
"48 - - - 8 ds = 6 ? - - - - 1 32 - - - - 8 us = 4 ? - - - - 1 s = ? s = ( 6 - 4 ) / 2 = 1 answer : a"
divide(add(divide(32, 8), divide(48, 8)), const_2)