There are a few people on the first floor, the second floor and the third floor. You can talk nonsense then. This is the first question of the seventh grade mathematics basic training. Why is it all history? Please, no, stop it, okay?

The correct answer is:

Let the length of the Great Wall built by Qin, Han and Ming be x, 2x, 1.27x(km) respectively.

According to the meaning of the question

2x- 1.27x=3650

The solution is x=5000.

Then 2x = 10000, 1.27x = 6350.

Therefore, the length of the Great Wall built in Qin Dynasty, Han Dynasty and Ming Dynasty is 5000 km, 10000 km and 6350 km respectively.

I hope the landlord will adopt it! ! ! ! ! ! ! ! !