A man can row his boat with the stream at 19 km/h and against the stream in 11 km/h. The man's rate is? Choose one.
A) 4 kmph
B) 2 kmph
C) 7 kmph
D) 8 kmph
E) 3 kmph

Rationale: "ds = 19 us = 11 s = ? s = ( 19 - 11 ) / 2 = 4 kmph answer : a"
Answer: A