A man can swim in still water at 9 km/h, but takes twice as long to swim upstream than downstream. The speed of the stream is?  Choose the correct choice
A) 1.7 B) 1.4 C) 3 D) 1.5 E) 1.9
M = 9   S = x   DS = 9+ x   US = 9 + x   9 + x = (9 - x)2   9+ x = 18 -2x   3x = 9   x = 3   Answer:3
<result>C</result>
A man can swim in still water at 9 km/h, but takes twice as long to swim upstream than downstream. The speed of the stream is?