Need Help on 4b, heres 4a and my answer followed by 4b.

4a. You purchased 1,000 shares of the Terrier Fund at a price of $20 per share at the beginning of the year. You paid a front-end load of 4.5%. The securities in which the Fund invests increase in value by 13% during the year. The Fund's expense ratio is 1% and it is charged in arrears at the end of each year. a) What is your rate of return on the Fund if you sell your shares at the end of the year?

I got 6.96% for 4a

4b. Now assume the Fund charges a back-end load instead of a front-end load. The load is still 4.5%, but it declines in a linear manner down to zero over a three-year period, with each step-wise decline of 1.5% occurring on the anniversary of the date you purchased the fund. If all of the other conditions described above remain unchanged, what is your rate of return on the Fund if you sell your shares after holding them for exactly one year?