The simple interest on a certain sum of the money at 4 % per annum for 4 years is Rs.80 more than the interest on the same sum for 3 years at 5 % per annum. Find the sum.

The difference between the compound interest and simple interest of a certain sum of amount is rupees 256.40 for 4 years at 10% rate per annum. Find the sum of money?

The simple interest on a sum  of money is of the sum. If the number of years is numerically half the rate percent per annum, then the rate percent per annum is 

An amount doubles itself in 5 years simple interest. What is the rate of interest per year?

A sum of ₹ 10,000 is lent partly at 8 % and remaining at 10% per annum. If the yearly interest on the average is 9.2 %, the two parts are 

Which amount will be Rs 520 in 5 years with simple interest and Rs 568 in 7 years?

In what time will the simple interest be of the principal at 8% per annum? 

A sum of money at double the rate of simple interest doubles itself in 10 years. In how much time will that amount be triple of itself?