A man rows his boat 84 km downstream and 60 km upstream, taking 4 hours each time. Find the speed of the stream?	Pick one:
A) 76 kmph
B) 6 kmph
C) 14 kmph
D) 8 kmph
E) 3 kmph

Rationale: "speed downstream = d / t = 84 / ( 4 ) = 21 kmph speed upstream = d / t = 60 / ( 4 ) = 15 kmph the speed of the stream = ( 21 - 15 ) / 2 = 3 kmph answer : e"
Answer: E