<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?
<bot>: 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.
#### 8