a swimmer swims downstream 55 km and upstream 10 km taking 5 hours each time ; what is the speed of the current ?
55 - - - 5 ds = 11 ? - - - - 1 10 - - - - 5 us = 2 ? - - - - 1 s = ? s = ( 11 - 2 ) / 2 = 4.5 answer : b
divide(subtract(divide(55, 5), divide(10, 5)), const_2)