David borrowed a sum of ₹24,000 at a fixed simple interest rate for 2 years. If he paid ₹6,000 as interest at the end of the term at an annual interest rate of x%, what is the value of x?

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?