A man swims downstream 30 km and upstream 20 km taking 5 hours each time, what is the speed of the man in still water?
Choose the correct choice from the following answers
A) 7 B) 8 C) 2 D) 5 E) 4
30 --- 5 5S = 6   ? ---- 1   20 ---- 5 US = 4   ? ---- 1 M = ?   M = (6 + 4)/2= 
<gadget id="calculator">(6 + 4)/2</gadget>
<output>5</output>
5   Answer:5
<result>D</result>
A man swims downstream 30 km and upstream 20 km taking 5 hours each time, what is the speed of the man in still water?