a man swims downstream 35 km and upstream 20 km taking 5 hours each time , what is the speed of the man in still water ?
"35 - - - 5 ds = 7 ? - - - - 1 20 - - - - 5 us = 4 ? - - - - 1 m = ? m = ( 7 + 4 ) / 2 = 5.5 answer : b"
divide(add(divide(20, 5), divide(35, 5)), const_2)