I believe this is correct because when you solve for x, it gives you the price per month. When you multiply the price per month ($27.50) times 12+150, you do get the $480.
How I got this was that I started with 480 and subtracted the 150 fee because thats a one time payment. then I divided 330/12 to give me the price per month which is the (27.50). You want x to be dollars, so I made it 12x rather than 27.50x because if it was 27.50x, x would be in months, not dollars.
