The sum of the digits of a two-digit number is 9. If 27 is subtracted from the number, then the digits interchange their places. Find the number

Explanation

To solve the problem, let's denote the two-digit number as \( 10a + b \), where \( a \) is the tens digit and \( b \) is the units digit.

### Step 1: Set up the equations based on the problem statement.

1. **Sum of the digits**: The sum of the digits of the number is given as 9.
\[ a + b = 9 \quad \text{(Equation 1)} \]
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