a man rows his boat 84 km downstream and 48 km upstream , taking 2 hours each time . find the speed of the stream ?
"speed downstream = d / t = 84 / ( 2 ) = 42 kmph speed upstream = d / t = 48 / ( 2 ) = 24 kmph the speed of the stream = ( 42 - 24 ) / 2 = 9 kmph answer : c"
divide(subtract(divide(84, 2), divide(48, 2)), const_2)