A man can swim in still water at 7.5 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 choices.
A) 3
B) 2.5
C) 2.25
D) 1.5
E) 4

Rationale: "m = 7.5 s = x ds = 7.5 + x us = 7.5 - x 7.5 + x = ( 7.5 - x ) 2 7.5 + x = 15 - 2 x 3 x = 7.5 x = 2.5 answer : b"
Answer: B