A man can swim in still water at 6 km/h, but takes twice as long to swim upstream than downstream. The speed of the stream is?	Choose the correct choice from the following
A) 3	B) 7.5	C) 2.25	D) 2	E) 4

Rationale: "m = 6 s = x ds = 6 + x us = 6 - x 6 + x = ( 6 - x ) 2 6 + x = 12 - 2 x 3 x = 6 x = 2 answer : d"
Answer: D