​A sum of money at simple interest amounts to Rs.815 in 3 years and to Rs.854 in 4 years. The sum is:

Correct option is C

Given:

A sum of money at simple interest amounts to Rs.815 in 3 years and to Rs.854 in 4 years.

Solution:

In simple interest, every year interest is same received.

(Principle + Interest) in 3 year = 815

(Principle + Interest) in 4 year = 854

One year interest = 854 - 815 = 39

So, 39 is one year interest then 3 years interest = 39 × 3 = 117

The principal (sum of money) is the amount after subtracting the simple interest for 3 years:

Principal = 815 − 117 = Rs 698

Thus, the correct answer is (c).