OK.....I'll take a stab at this one.
We have, after one year
V = 25000e^(T*N)
Where "V" is the value of the car after T years. We need to find "N"
So, we have (after 1 year)
21250 = 2500e^(1*N)
Divide both sides by 25000
(21250/25000) = e^(1*N)
Now, take the LN of both sides
LN(21250/25000) = LN e^(1*N)
By the property pf logs, the LN e^(1*N) just becomes (1 * N) or just N !!
So we have
LN(21250/25000) = N
Since this is just a messy decimal, let's leave N as it is!!
So, our function is
V = 25000e^(T * LN(21250/25000))
To find the value after 5 years we have
25000e^(5*ln(21250/25000))
About....... $11092.63
I think that's it!!