(v- 5/3) * 20 = 300

V = 50/3m/s = 60km/s

Pay attention to coming from the back, so the train and Xiao Ming are in the same direction, and the speed is subtracted.

2

120t + 50 + 80t = 450

T = 2 (hours)

-Go in the opposite direction and add up the speed (I really don't know how to draw)

3 yes

The principle is the same as before, except that there is a lovely puppy.

Find the time first, the time when they met T.

6t+4t = 1000, so t = 100 seconds.

The puppy has run for 100 second, so the distance the puppy runs is100 *10 =1000 meter.

5 Let the distance be S kilometers and the plane speed be V kilometers per hour.

Downwind, speed sum: (V+20)* 10/3 = S

Against the wind, speed subtraction: (V-20)*4 =S

Solution, S=800 km, v = 220 km/h.

six

Think for yourself, how many kilometers did two people walk from morning to noon 10/2? Set to s kilometers.

Think about yourself first. After getting S, both of them are uniform, so it takes two hours from 8 am to 10, and the road is also S kilometers.

So AB = S+36(km)- After S km, there is still 36 km left, so add it up.

What is s? Have you figured it out? I hope you can figure it out yourself. You have to use your head in math. I'll tell you if I can't figure it out.

S = 72km, two people meet 36km, then walk to each other, and then walk back to each other. The final distance is 36km, so the distance is 36+36 = 72km.

The distance of AB is 72+36 = 108km.