Carly deposits $900 into an annuity at the end of every month for 2.5 years. The fund holds international stocks, and it yields about 12% compounded monthly. Find the interest earned after 2.5 years.
a.$31,619.46
b.$31,306.40
c.$4,619.47
d.$4,306.40
(I can not figure this out, so please if you could walk me through it. )