The following charts are 10 data extracted from the results of boys' 1000m running and girls' 800m running Boys No.1 and No.10 start running around the 400 meter track in the same direction at the same time. Can they meet for the first time in the 1000 meter run? If they can, find out the time required; if they can't, explain the reason. (boys No.1 score 3'10, boys No.10 score 3'55) Suppose that after X minutes, No. 1 and No. 10 can meet for the first time in the 1000 meter race 1000 /(35/ 60) x-1000 /3(55/ 60) x=400 ∴300x=1739 ∴x≈5.8 5 ′ 48 ″ > 3 ′ 05 ″, Candidates 1 and 10 cannot meet for the first time in the 1000 meter race In the process of solving this problem, why 1000 / (35 / 60) x-1000 / 3 (55 / 60) x = 400, x = 400? How did it come from?

(3) No. 1 and No. 10 can meet for the first time in the 1000 meter race after X minutes

Xiao Ming climbs the mountain. When he goes up the mountain, he walks 30 meters per minute. When he goes down the mountain, he goes back along the original road and walks 40 meters per minute. What's the average speed of Xiao Ming going up and down the mountain?
Formula: 2 ^ (1 / 30 ^ 1 / 40) what does this formula mean
What I want is the meaning of this formula

Set the distance to 1
The round trip distance is 1 + 1 = 2
The time is 1 / 30 and 1 / 40 respectively
Speed = 2 ^ (1 / 30 ^ 1 / 40)

According to the formula: average speed = total distance △ total time
Total distance: 2A
Total time: 2.5
So the average velocity is 2A △ 2.5 = 0.8A