The difference of simple interest from two banks on ₹8,000 in 3 years is ₹800. If the rate of interest per annum in two banks are R1 and R2, then what is the value of R1 - R2? (Where R1 > R2)

A person invested some amount at the rate of 12 % simple interest and a certain amount at the rate of 10 % simple interest for 1 year. He received yearly interest of Rs. ₹ 130, but if he had interchanged the amount invested, he would have received 4 more as interest. How much did he invest at 12 % simple interest? 

If the simple interest on a certain sum of money for 2 years in one fifth of the Principal, then find rate of interest per annum. 

Any money at the rate of simple interest becomes Rs 1143 in 3 years and Rs 1305 in 5 years Find the rate of principal and interest.

A sum of money lent out at simple interest amounts to ₹720 after 2 years and 1020 after a further period of 5 years. Find the principal. 

The difference between simple interest and compound on Rs. 1200 for one year at 10% per annum reckoned half-yearly is:

A certain sum doubles in 7 years at simple interest. The same sum under the same interest rate will become 4 times in how many years.:

The simple interest on an amount at the rate of 13.5 p.c.p.a. for 10 years is Rs. 765.45. What is the sum?