The resale value of the car after two years is given by `R(t) = 20000*0.86^t` .

The rate of depreciation of the car is `(d(R(t)))/dt` .

`(d(R(t)))/dt = 20000*ln(0.86)*0.86^t`

The rate of depreciation after :

1 year : -2594.15

2 years: -2230.97

3 years: -1918.63