7. This year, Xiaobing is 7 years old, and Xiaobing's mother is 35 years old, (）years later, the mother's age will be 3 times Xiaobing's age.
【Answer】 7 years later.
【Analysis】Exam point: Age problem
Age difference: $35-7=28$ (years) One unit quantity: $28 \div(3-1)=14$ (years) Need to wait: 14-7=7 (years)