a man rows his boat 78 km downstream and 56 km upstream , taking 4 hours each time . find the speed of the stream ?
"speed downstream = d / t = 78 / ( 4 ) = 20 kmph speed upstream = d / t = 56 / ( 4 ) = 14 kmph the speed of the stream = ( 20 - 14 ) / 2 = 3 kmph answer : e"
divide(subtract(divide(78, 4), divide(56, 4)), const_2)