A woman swims downstream 54 km and upstream 6 km taking 6 hours each time, what is the speed of the woman in still water?  Choose the most appropriate option:
A) 2	B) 3	C) 4	D) 5	E) 6
54 --- 6 5S = 9   ? ---- 1   6 ---- 6 US = 1   ? ---- 1 M = ?   M = (9 + 1)/2= 
<gadget id="calculator">(9 + 1)/2</gadget>
<output>5</output>
5   Answer:5
<result>D</result>
A woman swims downstream 54 km and upstream 6 km taking 6 hours each time, what is the speed of the woman in still water?