I'll give you a question, please answer with step-by-step reasoning process.
If Beth is 18 years old and her little sister is 5, in how many years would she be twice her sister's age?

8
The age difference between Beth and her sister is 18 - 5 = 13 years.

Beth must be 13 x 2 = 26 to be twice her sister's age.

Beth will be twice her sister's age in 26 - 18 = 8 years.

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The final answer: 8