How old is the middle-aged person mentioned in the eight characters?

As usual, the middle-aged man is a bit vague:

1, the literal interpretation of middle age is the middle stage of a person's life. He used to live 60, with a middle of 30-45; Now the average life expectancy is 70, which can be set at 30-49.

2. It depends on the age or fate of the Universiade, between 25 and 60 years old.

3. People's life span is 108 years old, sometimes it can be between 37 and 72 years old.