The photography team is a day's journey from City A to City B, and it is planned to walk 100 km more in the morning than in the afternoon to go to City C for dinner.

Let AD=a

DC=b

CE=c

EB=d

AC is the planned morning trip, so a+b=c+d+ 100 (1).

AD is the actual distance traveled in the morning, so a=b/2, which means 2a=b (2).

After lunch, I set out from the small town D and arrived at E to rest in the evening. I have walked 400Km, which means b+c=400? (3)

During the night break, the driver said that if you walk half the distance from C to here, you will arrive at the destination B, and then there will be c=2d (4).

Substitute (2) and (4) into (1), and there is b-c=200/3 (5).

Combine the two formulas (3) and (5) to get b=200+ 100/3.

c=200- 100/3

Substituting (2) and (4) can get a= 100+50/3.

d= 100-50/3

It can be concluded that the distance from AB to two cities is AB=a+b+c+d=600Km.