f time upstream = n $$\times$$ time downstream and speed in still water is 'x' and speed of stream is 'y', then find x : y.

A

$$\frac{n}{2}$$

B

$$\frac{n+1}{n-1}$$

C

$$\frac{n}{n-1}$$

D

$$(\frac{n-1}{n+1}$$)