The formula for calculating simple interest is expressed as
I = PRT
where
I represents interest
P represents principal or initial amount
R represents interest rate
T = time in years
From the information given,
P = 3200
R = 9/100 = 0.09
T = 45 days. We would convert it to years. Since there are 360 days in one year,
T = 45/360 = 0.125
By substituting these values into the formula,
I = 3200 x 0.09 x 0.125 = 36
Simple interest = $36
Total amount = principal + interest
Total amount = 3200 + 36 = $3236