a man swims downstream 16 km and upstream 10 km taking 2 hours each time , what is the speed of the man in still water ?
"16 - - - 2 ds = 8 ? - - - - 1 10 - - - - 2 us = 5 ? - - - - 1 m = ? m = ( 8 + 5 ) / 2 = 6.5 answer : c"
divide(add(divide(10, 2), divide(16, 2)), const_2)