Multiple choice

Five years ago, the ratio between ages of A and B was 3: 4. After five years from now the ratio between their ages will be 5: 6. Find the present age of A.

  1. 22 years

  2. 25 years

  3. 15 years

  4. 20 years

  5. 18 years
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Let present ages be A and B. Five years ago: (A-5)/(B-5) = 3/4, so 4A - 20 = 3B - 15, or 4A - 3B = 5. After five years from now: (A+5)/(B+5) = 5/6, so 6A + 30 = 5B + 25, or 6A - 5B = -5. Solving: A = 20, B = 25. Present age of A is 20 years, matching option D.

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