Rachana borrowed a certain sum at the rate of 15% per annum. If she paid at the end of two years Rs 1290 as interest compounded annually, find the sum she borrowed.

Explanation

To find the sum Rachana borrowed, we can use the formula for compound interest. Here’s the step-by-step solution:

### Step 1: Understand the formula for Compound Interest
The formula for compound interest (CI) is given by:
\[ CI = A - P \]
Where:
- \( CI \) = Compound Interest
- \( A \) = Amount after time \( t \)
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