7. An amortized loan made at an effective interest rate of 6.6% is to be repaid over a period of fifteen years by annual end-of-year payments of $1800. What proportion of the loans total interest is paid back in the first five years? a) At the end of five years a $5000 payment is made to reduce the amount of the loan at b) which point the required level annual payments for the remaining 10 years are reduced to $X. Determine X