Help to make a junior three equation Thank you for applying the equation!

X cars of type B going to A, then 20-x cars of type A going to A, 10-x cars of type B going to B, and 20-(20-x) = x cars of car A going to B.

y=(20-x)*1000+x*900+x*800+(10-x)*600

y=20000-1000x+900x+800x+6000-600xy=26000+300x

According to the title: 0 x 10

0≤20-x≤20-->0≤x≤20

0≤10-x≤10-->0≤x≤10

0≤x≤10

In summary, the value range of x is as follows:

0≤x≤10

Let's start with it, maybe there is an answer.

X cars B going to A, vehicle A (20-x) going to A, vehicle B (10-x) going to B, car A X going to B.

y＝1000*(20-x)+900*x+800*x+600*(10-x)

100x+26000

The value of x can be greater than or equal to 0 and less than or equal to 10, that is, 0<=x<=10

Let B x go to A, then go to A20-x of A, go to B 10-x, and go to B Xy=1000x+800*(20-x)+900x+600(10-x)22000-500x

0<=x<=10

Set the walking speed of junior high school students x

10 x is the time spent by junior high school students.

10 (6+x) hours spent by high school students.

10/x=10/(x＋6)+

x = 4 km/h.

The answer on the first floor is wrong. No answer on the second floor.

Set: Walking speed is x km/h.

Then: 10 x = 10 (x 6).

Solution: x=4 or x=10.

A: The walking speed is 4 km/h.

Solution: If the walking speed of junior high school students is xkm h, then:

10/x-10/(x+6)=

10(x+6)-10x=

10x+60-10x=

x^2+6x-40=0

x+10)（x-4)=0

x1 = 4 x2 = -10 (rounded).

That is, the speed at which junior high school students walk is 4 km h.

Solution: If the walking speed of junior high school students is x, then the cycling speed of high school students is x+6

10/x-10/（x+6）=1+

Solution: x=7

Take the equation of time equality: Let the velocity of junior high school students be x, then the velocity of high school students is x plus 6 columns: 10 x=10 (x+6)+

Simplifying the square of x plus 6x minus 40 equals 0

The solution is x1=4;x2 = minus 10 (rounded).

So x=4

If the walking speed of junior high school students is x km, the cycling speed of high school students should be x+6 km.

10/x=x 2 +6x-40=0

x=4 or x=-10

According to the inscription x=4

The speed at which junior high school students walk is x kilometers per hour.

10/x-10/(x+6)=1+30/60

x = 8 junior high school students walk at a speed of 8 km/h.

A and B are 8 kilometers apart, both of them set off at the same time, if they go in the same direction, A catches up with B; If they are walking in the opposite direction, meet in 1 hour, and find out what the speed of the two people is.

A train crosses two bridges at a speed of 840m per minute, the time to cross the second bridge is 4 seconds longer than the first bridge, and the second bridge is 100m shorter than 2 times, find the length of the two bridges.

Divided into two cuboids, the area of 2 square surfaces was originally 6 faces, but now it is 6 + 2 = 8 square area 4x4x (6 + 2) = 16x8 = 128 (square decimeters) Answer: The total area of spray painting is 128 square decimeters.

The area of one face of the cube.

162 2 = 81 (cm).

81=9x9

So the edge length of the cube is 9 centimeters.

The surface area of the box.

81x(2+4x2)=81x10=810 (square centimeters) box volume.

9x9x9x2 = 1458 (cubic centimeters).

162÷2=81

81x6x2-162=810

9x9x9x2=1458

The surface area of the assembled cuboid is 810 square centimeters and the volume is 1458 cubic centimeters.

Solution: If there is an X table, there are 12 (X-1) teachers.

Then 10(x+2)=12(x-1).

10x+20=12x-12

2x=32x=16

A: There are more than 180 teachers.

Solution: There are x number of teachers.

x÷12+1=x÷10 -2

x/10-x/12=2+1

x/60=3

x=180A: So there are 180 teachers in total.

Let the number of teachers be x, x 12)+1=(x 10)-2

x = 180 people.

Set up teachers x people, desks y only.

12（y-1)=x

10（y+2)=x

Solution: x=18 y=16

Solution: There are x tables with equations listed.

12（x-1）=10（x+2）

x=16, so there are 180 teachers.

There are x teachers and n desks, x = 12 (n-1).

x=10(n+2)

x=180n=16

1. Set Y products per box.

Then: (8y+4)-(11y+1)=1

2. The area that needs to be painted in each room is x square meters.

Then: (8x-50) 3-(10x+40) 5=10

If the 6-cornered bun x + 1, then the 4-cornered bun x, then the 7-corner bun 31-x-1-x = 30-2x

then (x+1)*

That is, x=8, that is, 4 corners of the bun 8, 6 corners of the bun 9, 7 corners of the bun 14.

There are x for 4 corners, x + 1 for 6 corners, 31 - (2x+1) for 7 corners, 4x+6(x+1)+7[31-(2x+1)] = 1844x+6x+6+210-14x=184

4x+216=184

4x = 32x = 8 for 84 corners, 9 for 6 corners, 14 for 7 corners.

The three kinds of buns have x, x+1, and y respectively 4 angles, 6 angles, and 7 angles, and 2x+1+y=31

The solution is y=14 x=8

There are 8 for the 4 corners, 9 for the 6 corners, and 14 for the 7 corners.