Multiple choice

A father is three times as old as his son. $5$ years ago, the father was four times as old as his son. After $5$ years, father's age will be

  1. $30$ years more than the son's age
  2. $25$ years more than the son's age
  3. $32$ years more than the son's age

  4. three times the son's age
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Let son's age be x, then father is 3x. Five years ago: 3x - 5 = 4(x - 5). Solving gives 3x - 5 = 4x - 20, so x = 15. Father is 45, son is 15. After 5 years, father is 50 and son is 20. The difference is 50 - 20 = 30 years.

AI explanation

Let the son's present age be S and the father's present age be 3S. Five years ago, the father was four times as old as his son, so 3S - 5 = 4(S - 5). Solving this equation gives 3S - 5 = 4S - 20, meaning S = 15, and the father's present age is 45. In any scenario, the constant age difference between a father and son is 45 - 15 = 30 years, so after 5 years, the father will still be 30 years older than his son.

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