Multiple choice

If twice the son's age is added to father's age, the sum is 75 and if twice the father's age is added to son's age the sum is 90. What is father's age?

  1. 35 years

  2. 40 years

  3. 45 years

  4. 50 years

  5. None of these
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A Correct answer
Explanation

Let son's age = S, father's age = F. First equation: 2S + F = 75. Second equation: S + 2F = 90. Solve the system: multiply first equation by 2: 4S + 2F = 150. Subtract second equation: (4S + 2F) - (S + 2F) = 150 - 90, giving 3S = 60, so S = 20. Then F = 75 - 2(20) = 35. Father is 35 years old.

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