A man can row his boat with the stream at 12 km/h and against the stream in 4 km/h. The man's rate is?	Pick one.
A) 1 kmph  B) 4 kmph  C) 98 kmph  D) 6 kmph  E) 4 kmph

Rationale: "ds = 12 s = ? s = ( 12 - 4 ) / 2 = 4 kmph answer : e"
Answer: E