Hi, this is a question in my actuarial class. Please help me solve it, thank you!

John and Mary each take out a 17-year loan of L. John repays his loan using the amortization method, at an annual effective interest rate of i. He makes an annual payment of 500 at the end of each year. Mary repays her loan using the sinking fund method. She pays interest annually, also at an annual effective interest rate of i. In addition, Mary makes level annual deposits at the end of each year for 17 years into a sinking fund. The annual effective rate on the sinking fund is 4.62%, and she pays off the loan after 17 years. Mary's total payment each year is equal to 10% of the original loan amount.

(a) Calculate L.

(b) With the 6th payment, John pays an extra 700, and then repays the balance over 5 years with a revised annual payment of X. Calculate X.