Multiple choice

The difference in the age of two people is 20 years. If 5 years ago, the elder one of the two was 5 times as old as the younger one, what is the present age of the younger one ?

  1. 15 years

  2. 10 years

  3. 30 years

  4. 20 years
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Let the elder age be E and younger be Y. E - Y = 20. Five years ago, (E-5) = 5(Y-5). E - 5 = 5Y - 25. Since E = Y + 20, substitute: (Y + 20) - 5 = 5Y - 25. Y + 15 = 5Y - 25. 4Y = 40, so Y = 10.

AI explanation

Let the present age of the younger person be y years; the elder person's present age is y plus 20. Five years ago, the elder person's age was y plus 15, and the younger person's age was y minus 5. Using the given condition, we write the equation y plus 15 equals 5 times (y minus 5), which simplifies to y plus 15 equals 5y minus 25. Solving this equation gives 4y equals 40, meaning the present age of the younger person is 10 years.

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