You deposit $4000 in an account that pays 9% interest compounded yearly.

Find the balance after 15 years.

I used this formula:

y = C(1 + r)^15

So I substitute:

y = (4000)(1 + .09)^15

y = (4000)(1.09)^15

Do I multiply the first two numbers before doing the power? Or do I do 1.09^15 first?