The age of the father is twice the sum of the ages of his two children. After 20 yr, his age will be equal to the sum of the ages of his children. Find the age of the father.

Explanation

To solve the problem step by step, we will define the variables and set up equations based on the information given in the question.

### Step 1: Define Variables
Let:
- \( x \) = the sum of the present ages of the two children
- \( y \) = the present age of the father

### Step 2: Set Up the First Equation
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