A man swims downstream 36 km and upstream 26 km taking 2 hours each time, what is the speed of the man in still water?
Choose the correct choice from the following options:	A) 9	B) 18.4	C) 15.5	D) 16.7	E) 13.4

Rationale: "36 - - - 2 ds = 18 ? - - - - 1 26 - - - - 2 us = 13 ? - - - - 1 m = ? m = ( 18 + 13 ) / 2 = 15.5 answer : c"
Answer: C