I have a quick question.

I keep getting confused in this topic.

Purchase down payment= $3000
add on number of payments = 18
price= $500
interest rate : 7%
FIND THE APR TO THE NEAREST HALF.

In my solution I am first calculating the total payment and then I get a 9000, once I am done with this, I calculate interest and then apply for the Finance charge formula.

However I am not getting anything close to the multiple choice given..

Could any one please help me solve this and show me?