You have an outstanding student loan with required payments of $$550$ per month for the next four years. The interest rate on the loan is $9\%$ APR $($monthly$).$ You are considering making an extra payment of $$150$ today $($that is$,$ you will pay an extra $$150$ that you are not required to pay$).$ If you are required to continue to make payments of $$550$ per month until the loan is paid off, what is the amount of your final payment? What effective rate of return $($expressed as an APR with monthly compounding$)$ have you earned on the $$150?$

If you are required to continue to make payments of $$550$ per month until the loan is paid off, what is the amount of your final payment?

The amount of your final payment is $$.($Round to the nearest cent.$)$

What rate of return $($expressed as an APR with monthly compounding$)$ have you earned on the $$150?$

Effective rate is $\%.($Round to the nearest integer.$)$