Multiple choice

Jack is three times as old as Mark. After 5 years, Jack will be twice as old as Mark. What is Jack's present age?

  1. 13 years

  2. 14 years

  3. 15 years

  4. 16 years

  5. 17 years
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let J = 3M. After 5 years, J+5 = 2(M+5). 3M+5 = 2M+10 -> M = 5. J = 3(5) = 15.

AI explanation

Let Mark's present age be x, making Jack's present age 3x. After 5 years, their ages will be x + 5 and 3x + 5, leading to the equation 3x + 5 = 2(x + 5). Solving this yields 3x + 5 = 2x + 10, so x = 5, which makes Jack's present age 3 * 5 = 15 years.

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