Help, i know the answer but i dont know how to get the answer. The explanation doesnt make sense to me. how do i solve??

Twelve years ago, your parents set aside $8,000 to help fund your college education. Today, that fund is valued at $23,902. What annually compounded rate of interest is being earned on this account? Multiple Choice 9.06% 9.67% 8.99% Explanation $23,902=$8,000[(1+r)12]r=.0955,or9.55%