Ermias and Ben plan to purchase a home for $$170,000.$ They will pay $20\%$ down and finance the remainder for $15$ years at the APR of $8\mathrm{.}4\%,$ compounded monthly.

a$)$ How large are the monthly payments? $

$1331\mathrm{.}00$

Correct

b$)$ What will be their loan balance right after they have made their $180$th payment? $

c$)$ How much interest will they pay during the $15$th year of the loan? $

d$)$ If they were to increase their montly payments by $$60,$ how long would it take to pay off the loan? Give your answer in whole months.