Question $1$

The Blakelys borrowed $$120,000$ from a bank to help finance the purchase of a house. The bank charges interest at

a rate of $9\%$ per year on the unpaid balance, with interest computations made at the end of each month. The

Blakelys have agreed to repay the loan in equal monthly installments over $30$ years. Find

a$)$ monthly payment $($annuity$)$

b$)$ total interest charges, and

c$)$ principal remaining at the end of year $15.$