Multiple choice

Rakesh is 60 years old and his brother is 70 years old. How many years ago was the ratio of their ages 4 : 5?

  1. 20 years

  2. 25 years

  3. 15 years

  4. 21 years

  5. 9 years
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Let the ratio of their ages be 4 : 5 at x years ago. We can set up the equation (60 - x) / (70 - x) = 4 / 5. Solving this equation gives 300 - 5x = 280 - 4x, which simplifies to x = 20 years.

AI explanation

Let the number of years ago be x, making the equation (60 - x) / (70 - x) = 4 / 5. Cross-multiplying yields 300 - 5x = 280 - 4x, which simplifies to x = 20. Therefore, the ratio of their ages was 4 : 5 exactly 20 years ago.

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