Jack, twenty one years old, is three times as old as his brother. How old will…
2024
Jack, twenty one years old, is three times as old as his brother. How old will Jack be when he is twice as old as his brother?
- A.
24
- B.
28
- C.
32
- D.
36
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Show answer & explanation
Correct answer: B
Solution:
Jack's current age is 21 years. His brother's age is 21 ÷ 3 = 7 years.
Let x be the number of years from now when Jack will be twice as old as his brother.
Set up the equation: (21 + x) = 2 × (7 + x).
Solve: 21 + x = 14 + 2x ⇒ 21 − 14 = 2x − x ⇒ x = 7.
Therefore Jack's age after 7 years will be 21 + 7 = 28 years.