= continuously compounded rate
= annually compounded rate
if you are still paying your annuities as annually, rather than continuously, then all you need to do is convert your "continuously compounded" interest rate into a normal one and then use the standard formula.
if you note that you will see whether or not you have the right answer.
More often the calculation of interest is the value of annuity paid continuously, which is a different concept to what you described above.