A and B set out from a and B at the same time, facing each other. After meeting, a continued to move forward and arrived at B for 18 minutes. B continued to move forward and arrived at a for 8 minutes. How many minutes did they meet after starting?

A and B set out from a and B at the same time, facing each other. After meeting, a continued to move forward and arrived at B for 18 minutes. B continued to move forward and arrived at a for 8 minutes. How many minutes did they meet after starting?

Let a walk a, B walk B, a speed x, B speed y, the equation is: ax = by & nbsp; & nbsp; & nbsp; & nbsp; ① 18x = B & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; ② 8y = A & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; ③ the solution is: xy = 23

Mathematical problems (solved by equation, only formula, not calculation)
1. A and B practice the 100 meter race. A runs 7 meters per second, B runs 6.5 meters per second. If B runs 1 second first, how many seconds can a catch up with B?
2. A and B are 285 meters apart and face each other. A walks 8 meters per second from a and B walks 6 meters per second from B. If a walks 12 meters first, how many seconds does a start to meet B?
3. The two trains of a and B are 144 meters and 180 meters long. Car a travels 4 meters more per second than car B. the two trains are facing each other. It takes 9 seconds from meeting to staggering. What's the speed of the two trains?

1、6.5+6.5x=7x
2. Let B be X
12 / 8 = 1.5 (SEC)
8x + 6x = 285-12 is X=
Then x + 1.5 is the required time
3. Let B be X
The total distance of a and B is: 144 + 180 = 324
(x+x+4)*9=324

You can't write equations, you can only write formulas
Kindergarten children are divided into apples. If each child has four apples, there will be nine more apples. If each child has five apples, there will be six less apples. How many children and how many apples are there?

9 + 6 = 15 (person)
4 * 15 + 9 = 69