# What will be the Sum? If

The simple interest on a certain sum at 5% per annum for 3 years and 4 years differ by Rs.42. The sum is

- Rs.210
- Rs.280
- Rs.750
- Rs.840

**Answer: (d) Rs. 840**

**Explanation:-**

**Given-** Rate = 5%, time = 4 – 3 = 1 year, interest = Rs.42

__Formula__:-

Simple interest = (P x R x T)/100 where, P = principal, R = rate, T = time

42 = (P x 1 x 5)/100

P = 840