In order to start a small business, Samy borrowed RM$40,000$ from a bank. The loan is repaid by monthly installment

for five years. The interest charged is $5\%$ on the original balance.

$($a$)$ Determine the monthly payment.

$($b$)$ Immediately after paying for three years and six months, he decided to pay off the loan. Using the Rule of $78,$

calculate the amount he has to pay.