Today Rebecca, who is 34 years old, and her daughter, who is 8 years

For this precise problem of age-doubling, I follow a simple reasoning.

Rebecca is 34 years old and her daughter is 8. Thus they’re 26 years apart from each other. While the daughter is younger than 26, her mom’s age will always more than double hers, whereas when she’s older than 26, the mom’s age will less than double hers. It is precisely at 26 that the daughter’s age will be doubled by her mom.

Why?
Let \(a =\)number of years Rebecca had lived before the daughter was born
Let \(b =\)number of years Rebecca has lived after her daughter’s birth
Let \(c =\)number of years the daughter has lived (after being born)

We are looking for:
(1) \(b - 8\), which will be the solution of the problem.

What the stem tells us is:
(2) \(a + b = 2c\)
(3) \(a = 26\)

What logic tells us is
(4) \(b = c\)

Thus:
(5) \(26 + b = 2b\) -> \(b = 26\)

From (1), we get the solution to the problem: \(26-8 = 18\)
Hope this helps!