a man swims downstream 45 km and upstream 25 km taking 5 hours each time , what is the speed of the man in still water ?
"45 - - - 5 ds = 9 ? - - - - 1 25 - - - 5 us = 5 ? - - - - 1 m = ? m = ( 9 + 5 ) / 2 = 14 / 2 = 7 answer : c"
divide(add(divide(25, 5), divide(45, 5)), const_2)