If you put $500 in a bank with a 6% investment rate (which is rather high honestly) then next year you would have $530 in the bank, then 561.80 and so on. I feel like I misunderstood the question, but hopefully this helps, if at all.
I'm honestly not too sure what exactly the question was implying, which means it could have been written better. I believe they are asking for you to multiply! So it would be 9*3, which would be 27. (3+3+3)
