If Beth is 18 years old and her little sister is 5, in how many years would she be twice her sister's age? Give me reasons, before answering the question
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. So the final answer is 8.