The difference between the S.I. and C.I. on a certain sum of money for 2 years at 4% per annum is Rs 20. Find the sum.

Explanation

To solve the problem step by step, we will find the principal sum of money (P) given that the difference between the Simple Interest (SI) and Compound Interest (CI) for 2 years at 4% per annum is Rs. 20.

### Step 1: Define the variables
Let the principal sum of money be Rs. x.

### Step 2: Write the formulas for SI and CI
- The formula for Simple Interest (SI) is:
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