Multiple choice

The ratio of present ages of X and Y is (3: 4). Five years ago, the ratio of their ages was (5: 7). What is the present age of Y?

  1. 50 years

  2. 40 years

  3. 60 years

  4. 30 years

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Let present ages be 3x and 4x. Five years ago: (3x-5)/(4x-5) = 5/7. Cross-multiply: 7(3x-5) = 5(4x-5), giving 21x-35 = 20x-25, so x = 10. Y's present age = 4x = 40 years. Option A assumes 5:7 is the present ratio, C mis-solves the equation, and D doesn't satisfy the conditions.