Yue Yue and her mother are 42 years old. She is 26 years younger than her mother. How old is Yue Yue?

This is a very simple binary linear equation. We can assume that the mother's age is X, the month age is Y, x+y=42y-x=26, and the answer is x=8, that is, the month age is equal to 8 years old.

Generally, this kind of problem is called binary linear equation problem in mathematics. The solution to this kind of problem is relatively simple. We can learn the most basic knowledge by opening books, and we can easily solve such problems.