7. This year, Xiaobing is 7 years old, and Xiaobing's mother is 35 years old. In ( ) years, the mother's age will be 3 times Xiaobing's age.
【Answer】7 years later.
【Analysis】Exam point: Age problem
Xueersi corresponding lecture: Grade 3 Autumn Class Age Problem (Lecture 10).
Age difference: 35-7=28 (years) One unit: $28 \div(3-1)=14$ (years)
Need to pass: 14-7=7 (years)