Brianna's car
Explanation:
Looking at the first equation the car decreases by 15% each year.
So our depreciation rate is 15%
The second equation represents an exponential depreciation with a depreciation rate given by;
1-0.9=0.1×100=10%
So our depreciation rate is 10%
Of course Brianna's car is decreasing in value quicker, since the car loses more value as the depreciation rate is higher.