The difference between simple interest on a certain sum at the annual rate of 10 percent for 7 years and 8 years is Rs. 57. What is the sum?

Correct option is C

Given:
Difference in time = 1 year
Rate of interest = 10%
Difference in interest = Rs. 57
Solution:
Simple Interest (SI) = P ×R ×T / 100
Difference in interest = P ×R ×(T2 - T1) / 100
57 = P ×10 ×1 / 100
P = (57 ×100) / 10 = Rs. 570
Thus, the sum is Rs. 570.