an woman swims downstream 45 km and upstream 25 km taking 5 hours each time ; what is the speed of the current ?
"45 - - - 5 ds = 9 ? - - - - 1 25 - - - - 5 us = 5 ? - - - - 1 s = ? s = ( 9 - 5 ) / 2 = 2 answer : a"
divide(subtract(divide(45, 5), divide(25, 5)), const_2)