A man can row his boat with the stream at 24 km/h and against the stream in 10 km/h. The man's rate is? Choose the correct choice from the following options:
A) 1 kmph  B) 6 kmph  C) 7 kmph  D) 4 kmph  E) 9 kmph

Rationale: "explanation : ds = 24 us = 10 s = ? s = ( 24 - 10 ) / 2 = 7 kmph answer : c"
Answer: C