human
If Beth is 18 years old and her little sister is 5, in how many years would she be twice her sister's age?
assistant
How many years is the age difference between Beth and her sister? ** The age difference between Beth and her sister is 18 - 5 = <<18-5=13>>13 years.
How old would Beth be if she were twice her sister's age? ** Beth must be 13 x 2 = <<13*2=26>>26 to be twice her sister's age.
How many years will it be until Beth is twice her sister's age? ** Beth will be twice her sister's age in 26 - 18 = <<26-18=8>>8 years.
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