Multiple choice

Five years ago, the age of a father was thrice the age of his son. In five years time, the age of the father will be twice the age of his son at that time. Find their present ages.

  1. Present age of father is $60$ years and present age of son is $20$ years
  2. Present age of father is $35$ years and present age of son is $15$ years
  3. Present age of father is $65$ years and present age of son is $25$ years
  4. Present age of father is $50$ years and present age of son is $15$ years
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Let F and S be current ages. (F-5) = 3(S-5) => F = 3S - 10. (F+5) = 2(S+5) => F = 2S + 5. Equating: 3S - 10 = 2S + 5 => S = 15. Then F = 2(15) + 5 = 35.

AI explanation

Let the present age of the father be F and the son be S. Five years ago, F minus 5 equaled 3 times (S minus 5), simplifying to F equals 3S minus 10. Five years hence, F plus 5 will equal 2 times (S plus 5), simplifying to F equals 2S plus 5. Equating the two expressions for F gives 3S minus 10 equals 2S plus 5, meaning S equals 15. Substituting 15 for S gives the father's present age as 35 years.

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