A man swims downstream 18 km and upstream 12 km taking 3 hours each time, what is the speed of the man in still water?	Choices:
A) 3
B) 5
C) 6
D) 4
E) 8
18 --- 3 DS = 6   ? ---- 1   12 ---- 3 US =4   ? ---- 1 M = ?   M = (6+4)/2= 
<gadget id="calculator">(6+4)/2</gadget>
<output>5</output>
5   Answer: 5
<result>B</result>
A man swims downstream 18 km and upstream 12 km taking 3 hours each time, what is the speed of the man in still water?