Given,
P=$4500
r=12%
For 1 month the rate is 12/12%=1%
So interest for one month is
a. The monthly payment is:
The monthly payment is $422.5
b. Total payment for a year is:
A=4500+(12x45)=$5040
Total amount paid since January is $5040
c. The percentage of interest is:
The percentage interest is 10.71%