Multiple choice

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

  1. $30$ years
  2. $35$ years
  3. $40$ years
  4. $22$ years
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let F be father's age, S be sum of children's ages. F = 2S. After 20 years, F + 20 = (S + 2*20) = S + 40. Substitute F = 2S: 2S + 20 = S + 40 => S = 20. F = 2 * 20 = 40.

AI explanation

Let the sum of the children's present ages be x years, making the father's present age 2x years. After 20 years, the father's age will be 2x plus 20 and the sum of the children's ages will be x plus 40. Equating the future ages gives 2x plus 20 equals x plus 40, which means x equals 20. The father's present age is 2 times 20, which is 40 years.

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