A man can row his boat with the stream at 22 km/h and against the stream in 10 km/h. The man's rate is?	Choose the correct choice from the following answers.
A) 1 kmph B) 6 kmph C) 7 kmph D) 4 kmph E) 9 kmph

Rationale: "explanation : ds = 22 us = 10 s = ? s = ( 22 - 10 ) / 2 = 6 kmph answer : b"
Answer: B