So firstly, we have to find out what 9% of $1,512 is. We can do this by multiplying 0.09(decimal form of 9%) and 1512 together, which gets you $136.08. This is the interest.
Next, add $136.08 and $1,512 together, which is 1648.08. This is the amount he needed to pay.
Now to find out how much he did pay, multiply 0.82 (decimal form of 82%) and 1648.08 together, which gets you 1351.43. $1351.43, or A, was the amount that Joel paid.