Multiple choice

The age of a is three times the sum of the ages of his two sons. Five years hence, his age will double the sum of ages of his sons. What is the father's present age?

  1. 45 years

  2. 30 years

  3. 50 years

  4. 60 years
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A Correct answer
Explanation

Let F be father's age and S be sum of sons' ages. F = 3S. In 5 years: F + 5 = 2(S + 10). Substitute F = 3S: 3S + 5 = 2S + 20. S = 15. F = 3 * 15 = 45.

AI explanation

Let the sum of the present ages of the two sons be x, which makes the father's present age 3x. In five years, the sum of the sons' ages will be x plus 10 and the father's age will be 3x plus 5; the equation becomes 3x plus 5 equals 2 times (x plus 10). Solving this linear equation gives 3x plus 5 equals 2x plus 20, so the father's present age is 3 times 15, or 45 years.

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