A man swims downstream 28 km and upstream 12 km taking 2 hours each time, what is the speed of the man in still water?	Choose the correct answer
A) 10	B) 8	C) 5	D) 2	E) 4

Rationale: "28 - - - 2 ds = 14 ? - - - - 1 12 - - - - 2 us = 6 ? - - - - 1 m = ? m = ( 14 + 6 ) / 2 = 10 answer : a"
Answer: A