Multiple choice

18 years ago, a man was three times as old as his son. Now, the man is twice as old as his son. The sum of the present ages of the man and his son is ?

  1. 72 years

  2. 54 years

  3. 105 years

  4. 108 years

  5. None
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Let man be M, son be S. M-18 = 3(S-18) => M-3S = -36. M = 2S. 2S-3S = -36 => S = 36. M = 72. Sum = 36+72 = 108.

AI explanation

Let the present age of the son be x years, so the father is 2x years old. Eighteen years ago, the equation is 2x minus 18 equals 3 times (x minus 18), which simplifies to 2x minus 18 equals 3x minus 54, giving x equals 36. The father is 72 years old and the son is 36 years old, so the sum of their present ages is 108 years.

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