Mr. Liu said to Xiaotian, "my age 18 years ago is the same as your age 6 years later. Five years ago, my age was seven times your age. How old is Xiaotian this year?

Mr. Liu said to Xiaotian, "my age 18 years ago is the same as your age 6 years later. Five years ago, my age was seven times your age. How old is Xiaotian this year?

Teacher Liu is bigger than Xiaotian: 18 + 6 = 24
The age of Xiaotian five years ago: 24 (7-1) = 4
Xiaotian's age this year: 4 + 5 = 9
This is a problem of difference