Chapter 8.5, Problem 60E

Some mortgage agreements allow the borrower to make payments that are larger than what is required. Because this extra money goes toward reducing principal, increasing your payments may allow you to pay off the mortgage many years earlier, thus saving great amount of interest. Assume you take out 30-year amortized loan at 8% for $\$100,000$ and your monthly payments will be $\$733.77$. Suppose that instead of making the specified payment, you increase it by $\$100$ to $\$833.77$. How much do you save on interest over the life of the loan if you make the larger payment?