Two banks, A and B, offered loans at 3.5% and 7.5% per annum simple interest, respectively. Nirmal borrowed an amount of ₹2,40,000 from each bank. Find the positive difference (in ₹) between the simple interest paid to the two banks by Nirmal after 2 years.

A sum becomes 2215 of itself in 6 years at simple interest. Find the rate of interest per annum.

In how many years will a sum of ₹5,500 amount to ₹6,600 at a simple interest rate of 5% per annum?

A sum of money amounts to ₹16000 in 6 years at simple interest of 25 percent per annum. What will be the total interest for 6 years?