We would apply the formula for determining simple interest which is expressed as
I = PRT/100
I is the interest
P is the principal or initial amount
R = interest rate
T = time in years
From the information given,
P = 1200
r = 18
Since there are 12 months in a year,
T = 9/12 = 0.75
Thus,
I = (1200 x 18 x 0.75)/100
Interest = $162
