a) In order to calculate the monthly payment for the amortization, we can use the formula:
Where A is the periodic payment amount, P is the principal amount, i is the interest rate and n is the total number of payments.
Since we have monthly payments, we can multiply the value of n (initially we have n = 9) by 12 and divide the interest rate by 12, so we have:
So the monthly payment is $117.81.
b) First let's calculate the total value paid:
Now, subtracting from the principal, we have the interest:
So the total interest is $4323.48.