The difference between compound interest and simple interest on a sum for 2 years at 8% P.a is Rs 786. The sum is:_________?

A. Rs 100000
B. Rs 11000
C. Rs 120000
D. Rs 170000
Explanation:
Let the sum be Rs x.
Then S. I = Rs (x × 8/100 × 2) = Rs 4x/25
C. I = Rs [x × (1 + 8/100)2 – x]
= Rs (x × 27/25 × 27/25 – x)
=Rs 104x/625 (C.I) – (S.I)
= Rs(104x/625 – 4x /25)
= Rs 4x /625
Therefore 4x/625 = 768
=> x = ((768 ×625)/4) = 120000
Therefore sum = Rs 120000