A man swims downstream 30 km and upstream 18 km taking 3 hours each time, what is the speed of the man in still water? Pick:	A) 9	B) 8	C) 5	D) 2	E) 1
30 --- 3 DS = 10   ? ---- 1   18 ---- 3 US = 6   ? ---- 1 M = ?   M = (10 + 6)/2= 
<gadget id="calculator">(10 + 6)/2</gadget>
<output>8</output>
8   Answer:8
<result>B</result>
A man swims downstream 30 km and upstream 18 km taking 3 hours each time, what is the speed of the man in still water?