The difference between the compound interest and the simple interest accrued on an amount of ₹ 18,000 in 2 years is ₹ 405. Find the rate of interest per annum.

The cost of a car, purchased 2 years ago, depreciates at the rate of 20% per year. If its present value is ₹ 3,15,600; find :

(i) its value after 2 years.

(ii) its value, when it was purchased 2 years ago.