1 When you put the goods, you can think of putting one of them in the carriage, but the other one can't fit at all, so not all carriages are loaded with two kinds of goods. therefore

If Class A goods are the main products, then: X car A, 50-x car B.

Yes: 35x+25(50-x)= 1530.

x=28

If class B goods are the main products, then: set up Y car in A and 50-y car in B.

Yes:15y+35 (50-y) =1150.

y=30

If the whole journey is counted as a unit, then the ordinary highway accounts for one third, and the expressway accounts for two thirds. Then let the ordinary expressway be xkm and the expressway be 2xkm.

Yes: x/60+2x/ 100=2.2.

X=60

Restrict the general highway to 60 kilometers, and the highway 120 kilometers.

3 If the scale value is x, the external angles are 3x, 4x and 5x. They are 6x respectively.

The sum of internal angles is 360; Available equations:

180-3x+ 180-4x+ 180-5x+ 180-6x = 360

X=20

The four angles are: 120, 100, 80, 60.

There are x people.

2x+3=3x-2

X=5

There are 13 bottles of mineral water.

Because it is said that the room is not full, there is one person missing. There are Class A rooms and X rooms, including:

4x- 1=3x+2

X=3

There are 1 1 boys in the class.

Tracing back to the problem, the sum of the trips of A is equal to the sum of the trips of B. Consider the limit cases on both sides. If it takes an hour to catch up with a, let b's speed be x.

5*2+5=x

X= 15

If it is 1.25 hours to catch up, there are still

5*2+5* 1.25= 1.25x

X= 13

Then the speed of B is controlled at 13 to 15 kilometers per hour.