I have a question if person borrows $9000 and makes yearly payment of 2684.8.what will be the interest he will earn. The answer is 15% but i couldnt get it.can anyone explain me how to calculate it

First, if he borrows the money he’s most likely paying interest, not earning interest.

Second, how many payments does he make? I’d infer five, but you didn’t make that clear.

If it’s 5, then:

PV = 9,000

FV = 0

PMT = −2,684.80

*n* = 5

Solve for *i* = 14.9994%

How can i get 15% manually do u know any formula?

first year = -9000

2nd year - 5th year = 2648.80

use IRR function in Excel and boom you get 15%

Do you have access to Google by any chance??

There is no simple, closed form solution to solve for the interest rate of an annuity. You have to iterate: some methods work faster than others.