Multiple choice

The ratio of present ages of A and B is 5 : 7. If the age of B after 10 years will be 31 years, then what is the present age (in years) of A?

  1. 10

  2. 15

  3. 25

  4. 35
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

B's age after 10 years is 31, so present age is 21. The ratio A:B is 5:7. If 7 units = 21, then 1 unit = 3. A's present age = 5 units = 5 * 3 = 15.

AI explanation

Let the present ages of A and B be 5x and 7x respectively. Since B's age after 10 years will be 31 years, you can write the equation 7x + 10 = 31. Solving this equation gives 7x = 21, so x equals 3. A's present age is 5x, which is 5 multiplied by 3, resulting in 15 years.

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