Nancy takes out a 20-year home loan of $500,000. The bank charges interest at 6.6% p.a. compounded monthly for the first 8 years and 7.2% p.a. compounded monthly thereafter. Nancy repays $3,757.36 each month end for the first 8 years. She increases the monthly repayment to $X after the first 8 years. Which of the following equations can be used to find the increased monthly repayment $X?