Multiple choice

The present ages of three friends A, B and C are in the ratio 3 : 5 : 7, respectively. Six years ago, the sum of their ages was 57. Find the present ages (in years) of A, B and C, respectively.

  1. 18, 30, 42

  2. 15, 25, 35

  3. 9, 15, 21

  4. 12, 20, 28

  5. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Let the ages be 3x, 5x, and 7x. Six years ago, their ages were (3x-6), (5x-6), and (7x-6). Their sum is 15x - 18 = 57, so 15x = 75 and x = 5. The present ages are 15, 25, and 35.

AI explanation

Let the present ages of A, B and C be 3x, 5x and 7x years. Six years ago, their ages were (3x minus 6), (5x minus 6) and (7x minus 6), and the sum of these ages is given as 57. Setting up the equation gives 3x minus 6 plus 5x minus 6 plus 7x minus 6 equals 57, which simplifies to 15x minus 18 equals 57. Solving for x gives 15x equals 75, so x is 5; multiplying this by the ratio values gives present ages of 15, 25 and 35.

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