Compute the finance charges on the following transaction due at the end of the billing period using (a) adjusted balance method, (b) previous balance method, (c) average daily balance method excluding current transactions, and (d) average daily balance method including current transactions. On August 31, the amount outstanding from the previous billing period is Rs. 500. No interest, which is compounded at 18 percent annually, is due if the bill is paid by September 30. On September 15, an additional charge of Rs. 500 is made. On September 20, a payment of Rs. 100 is made.