Multiple choice

$A$ is $20$ years older than $B. 5$ years ago, $A$ was $3$ times as old as $B$. Find their present ages.

  1. $50$ years and $30$ years
  2. $55$ years and $35$ years
  3. $60$ years and $40$ years
  4. $35$ years and $15$ years
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A = B + 20. (A - 5) = 3 * (B - 5). Substituting: (B + 20 - 5) = 3B - 15. B + 15 = 3B - 15. 2B = 30, B = 15. A = 35.

AI explanation

Let the present age of B be x years, making the age of A equal to x plus 20. Five years ago, the equation is x plus 15 equals 3 times x minus 5. Expanding gives x plus 15 equals 3x minus 15, so 2x equals 30 and x equals 15. The present age of A is 15 plus 20, which is 35 years, and the present age of B is 15 years.

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