A lady deposits $50 into a fund at the end of each quarter for 10 years. Determine the total amount of interest that she has accumulated at the end of 10 years if the fund earns 4.5% per year compounded annually for the first 5 years and 5% per year compounded semiannually for the second five years.

I'm getting confused on how you set it up to find the amount of interest. I think the total amount in the account at the end of the 10 years is: 50[(1.045)^20 - 1 / .045] + 50[(1.025^20 - 1 / .025] = 2845.81

But I dont understand how you figure out how much of that is the interest, or if you even need to caclulate the total amount at all...