A passenger car and a freight car leave from ab at the same time and run in opposite directions. The distance between AB and ab is 825km. Five hours after the two cars meet, the passenger car arrives at B. seven and two hours after the two cars meet, the freight car arrives at a. how many kilometers does the passenger car travel per hour?

The bus and the lorry are running in three hours
（1/4+1/5）×3=27/20
From meeting to departing of passenger cars and freight cars
This is an example. Suppose that the speed of a bus is x km / h and that of a train is y km / h
From the meaning of the title: 5x + 7.2y = 825
( 5x)/y = (7.2y)/x
The solution is x = 75 km / h

Party A and Party B travel from east to west at the same time and meet each other in six hours. Now Party A is 210 kilometers away from the west one hour after starting from the East, and Party B is 230 kilometers away from the east one hour after starting from the west at the same time

Solution
You can think of it like this, double the distance between the two places, and it's a good idea
Party A and Party B have to walk for 12 hours, one hour each, 210 + 230 kilometers apart
That is to say, the rest of the way is 10 hours' walk, 46 kilometers per hour,
Therefore, the actual distance between the two places is 46 * 6 = 276km

The two vehicles of a and B start from AB and run in opposite directions. When car a reaches 2 / 3 from B, car B exceeds the midpoint by 30 km. At this time, car a travels 45 km more than car B. how many kilometers is the distance between AB and B?

If vehicle B exceeds the midpoint by 30 km, then vehicle a has traveled 45 km more than vehicle B, then vehicle a exceeds the midpoint
30 + 45 = 75 (km)
The distance between a and B
75 (2 / 3-1 / 2) = 450 (km)

Which sea is the international standard of altitude?

It's not based on which sea. It's based on geoid
Geoid is a closed continuous surface drawn by mean sea level through continental extension
Generally speaking, it is a closed surface formed by the part of sea water extending below the land

There are three people, a, B and C, who walk 100 meters per minute, B 80 meters per minute and C 75 meters per minute. Now a starts from the East Village and B and C start from the West Village at the same time. Six minutes after a and B meet on the way, a and C meet again. So, what's the distance between the East and west villages?

Think of this problem as two encounter problems
(100 + 75) * 6 = 1050 (m) a and C walk together
1050 / (80-75) = 210 (minutes) a and B walk for each minute
210 * (100 + 80) = 37800 (m) total distance
I'm a fourth grader. I don't use equations

What is the highest temperature in Turpan Basin

The highest temperature in summer has a record of 49.6 ℃, and the average highest temperature from June to August is above 38 ℃. The highest temperature of sand surface at noon is 82.3 ℃, which has been called "Huozhou" since ancient times

On the 400 meter ring track, every day is 100 meters away from yunyun. Every day is in the front, and yunyun is in the back. They run forward in the same direction at the same time. Every day they run 4 meters per second, and yunyun runs 5 meters per second. Every person runs 100 meters, they have to stop and rest for 10 seconds. How many seconds does it take for yunyun to catch up with each other?

5-4=1
100÷1=100s
100×5=500 100×4=400
Four 10, three 10
So, 40 + 100 = 140s
Convert to minutes: 140 △ 60 = 2.33333 (infinite decimal)

What is the maximum temperature in summer and the minimum temperature in winter in Turpan

Turpan's highest temperature in summer is 49.6 degrees centigrade. Now it is about 47 degrees centigrade in summer. In winter, the temperature is more comfortable. I don't think it is more than minus 20 degrees centigrade

Both a and B started climbing from the bottom of the mountain at the same time. When they got to the top of the mountain, they immediately went down the mountain. Their speed of going down the mountain was twice as fast as that of going up the mountain. One hour after they started climbing, a and B met 400 meters away from the top of the mountain. When a came back to the foot of the mountain, B just reached the middle of the mountain. How long did B go back to the foot of the mountain later than a?

The topic is not clear, B just reached the hillside, is the hillside of the mountain, or the hillside of the mountain?
The above mountain road is "1"
Turn down mountain road into up mountain road
Suppose that both of them use the speed to walk up the mountain, and the downhill road is 1 / 2 of the uphill road
So the total distance is 1 + 1 / 2 = 3 / 2
|--------|----|
---Up the mountain down the mountain
1. If it's halfway up the mountain
When a returns to the foot of the mountain, the journey is 3 / 2
B: 1 / 2
The speed ratio of a and B is 3 / 2:1 / 2 = 3:1
When Party A and Party B met, they made a total of 2 times of the whole journey, which was 3 / 2 * 2 = 3
The second line: 3 / (3 + 1) = 3 / 4 of the whole process
3-3 / 4 = 9 / 4, 1 hour
It takes 3 / (9 / 4) * 1 = 4 / 3 hours for a to return to the foot of the mountain
It takes 4 / 3 * 3 = 4 hours for B to return to the foot of the mountain
B is later than a: 4-4 / 3 = 8 / 3 hours
2. If it's halfway down the mountain
When a returns to the foot of the mountain, the journey is 3 / 2
B: 1 + 1 / 2 * 1 / 2 = 5 / 4
The speed ratio of a and B is 3 / 2:5 / 4 = 6:5
When Party A and Party B met, they made a total of 2 times of the whole journey, which was 3 / 2 * 2 = 3
Among them, line B: 3 / (6 + 5) * 5 = 15 / 11
3-15 / 11 = 18 / 11, 1 hour
It takes 3 / (18 / 11) * 1 = 11 / 6 hours for a to return to the foot of the mountain
It takes 11 / 6 * 6 / 5 = 11 / 5 hours for B to return to the foot of the mountain
B is later than a: 11 / 5-11 / 6 = 11 / 30 hours

The absolute maximum temperature in summer appears in ()
A. Sichuan Basin B. Hainan Island C. Turpan Basin D. Xishuangbanna

The absolute maximum temperature is the extreme maximum temperature in the whole observation period, which represents the limit of temperature in a region. The hottest place in summer in China is Turpan in Xinjiang, where the extreme maximum temperature reached 49.6 ° and is called "Huozhou"