Erin borrowed $$200,000$ fixed$-$rate $30-$yr mortgage when mortgage rate was $4\mathrm{.}5\%.$ How much total interest will she pay if she does not pay off the mortgage earlier? She heard that some house buyers choose to make one extra monthly payment each year so as to pay off their mortgage earlier and therefore reduce the interest payment. Erin decided to do so too. Each year, she will split the extra payment to $12$ month so that she pays $$1098$ per month all the way until paying off the mortgage. Doing so will pay off her mortgage within $307$ months instead of $30$ years. How much interest will she save? If you were Erin and have extra money, are you financially better off by making extra monthly payment and paying off your mortgage earlier$|$