Ramya borrowed a loan from a bank for buying a computer. After 4 years she paid ₹ 26,640 and settled the accounts. If the rate of interest is 12% per annum, what was the sum she borrowed?

Find the simple interest on ₹ 3,500 at the rate of % per annum for 165 days.

In what period will ₹ 5,200 amounts to ₹ 7,384 at 12% per annum simple interest?

A sum of money triples itself in 8 years. Find the rate of interest.

A person purchases the following items from a mall for which the sales tax is mentioned against:

(a) Stationery materials for ₹ 250 and sales tax of 4% there on;

(b) Electronic goods worth ₹ 2,580 and sales tax of 10% there on;

(c) Groceries worth ₹ 1,200 on which sales tax of 3% is levied;

(d) Medicines worth ₹ 200 with sales tax of 6%. Find the bill amount for each item.