Since marnie has bought her car, the value has gone down 15%.if her car is 13000 right now, how much was it worth when she bought it?

Percentage of depreciation of the car that Marie bought = 15%
Present value of the car = 13000
Let us assume that the value of the car at the time of buying = x
So
The percentage valuation of the car now = (100 - 15) percent
                                                                 = 85 percent
Then
(85/100) * x = 13000
85x = 13000 * 100
85x = 1300000
x = 1300000/85
  = 15294.12
So the actual cost of the car is 15294.12. I hope the procedure is clear enough for you to understand.