Solution
For this case we can use the following model for a decay case given by:
y= a(b)^t
Where a= 13000
And b = 1-0.12 = 0.88
Where:
a = The initial value for this case is 13000 since is the starting price for the car
b = Represent the exponential decay factor and is defined as 1- fraction of decay. For this case fraction of decay = 12/100 = 0.12 and fo rthis reason b = 1-0.12= 0.88
So then the answer for this case is
b= 0.88