The answer above is correct, however, if you are seeing more of these questions in the future and don't know how to do it. you take the amount of sides (9) - 2 to get 7. Then multiply by 180 to get 1260. 1260/9 is 140
2 years is the same as 24 months, so the equation would be: 685 = 24x + 85, where x is the monthly fee. 600 = 24x 600/24 = x x = 25 The monthly fee is $25.