a man rows his boat 78 km downstream and 50 km upstream , taking 2 hours each time . find the speed of the stream ?
"speed downstream = d / t = 78 / ( 2 ) = 39 kmph speed upstream = d / t = 50 / ( 2 ) = 25 kmph the speed of the stream = ( 39 - 25 ) / 2 = 7 kmph answer : d"
divide(subtract(divide(78, 2), divide(50, 2)), const_2)