The two trains were running opposite each other at the same time. The first time they met was 4000 meters away from station a. the two trains were still running at the same speed, and they returned immediately after arriving at the same time Meet at 20 kilometers away from 100 million stations Detailed formula and

The two trains were running opposite each other at the same time. The first time they met was 4000 meters away from station a. the two trains were still running at the same speed, and they returned immediately after arriving at the same time Meet at 20 kilometers away from 100 million stations Detailed formula and

Is this the topic
The two trains run from station a to station B at the same time. The first time they meet is 40 kilometers away from station a. the two trains still run at the same speed. They return to each other's station immediately after arriving at each other's station. Then they meet 20 kilometers away from station B. how many kilometers are there between station a and station B?
If so
40×3-20=100km
perhaps
If the distance between the two places is s km, the speed of car a is x km / h, and that of car B is y km / h
According to the same travel time of the two vehicles when they meet, it is concluded that
40/x=(s-40)/y(s+20)/x=(2s-20)/y
Change the formula 40 / (S-40) = (s + 20) / (2s-20) = x / y
The solution is s = 100, s = 0

Xiao Zhang went to the railway station by the bus at his home. After driving one third of the time, he estimated that he would not be able to catch up with the time when the train arrived. So he got off the bus and changed to a taxi. The number of cars doubled. As a result, he arrived 5 minutes earlier by taxi than by bus and arrived at the railway station before the train arrived, How far is it from Xiaozhang to the railway station

Let Xiao Zhang Jia go to the railway station x km (x / 3) / 40 + (2x / 3) / (2 * 40) + 5 / 60 = x / 40 x = 10 km. Note: it takes one third of the time for the bus to go to the railway station: (x / 3) / 40, and the remaining two thirds of the time for the taxi: (2x / 3) / (2 * 40) 5 / 60 to arrive early

Xiao Zhang and his father are scheduled to take the bus at their home to the railway station. After a third of the journey, it is estimated that if they continue to take the bus, they will arrive at the railway station half an hour after the train starts. Once they get off the bus, they will take a taxi. The speed doubled. As a result, they arrive at the railway station 15 minutes before the train starts. The average speed of the known bus is 40 km / h, How far is Xiaozhang to the railway station
Xiao Zhang and his father are scheduled to take the bus at their home to the railway station. After a third of the journey, it is estimated that if they continue to take the bus, they will arrive at the railway station half an hour after the train starts. Therefore, they immediately get off the train and take a taxi. The speed doubled. As a result, they arrive at the railway station 15 minutes before the train starts. The average speed of the known bus is 40 km / h, How far is Xiaozhang to the railway station

The distance from Xiaozhang to the railway station is x km
X/40=(1X/3)/40+(2X/3)/40+15/60+30/60
The equation is as follows:
X/40=X/(40*3)+2X/(40*3*2)+45/60
3X/120=X/120+X/120+90/120
3X=X+X+90
X = 90 km
The establishment of the equation is based on: the total bus ride time = 1 / 3 bus ride time + 2 / 3 taxi ride time + 15 minutes in advance + 30 minutes if the bus is late
It's ten years since I graduated from university. I still remember my junior high school math. I feel young. Hahaha, I hope I didn't make a mistake