There is such a junior high school math problem, I don t know much about it, please answer it for me

Set up A-type steel plate X block, B-type steel plate Y block.

Then there is 2x+y=15 (x block a can make 2x block c, y block b can make y block c, a total of 15 blocks c is needed, so, 2x+y=15).

x+2y=18 (x block a can make x block c, y block b can make 2y block c, a total of 18 blocks d are needed, so, x+2y=18).

Solution, we get x=4, y=7

So there are 4 A-shaped steel plates and 7 B-shaped steel plates.

The meaning of the question should be that the A-shaped steel plate can be made into 2 C+1D, and the B-shaped steel plate can be made into 1C+2D

If you want to use the A-shaped steel plate x block and the B-type steel plate Y block, then the system of equations in the question column is obtained:

2x+y=15 （1）

x+2y=18 （2)

1) + (2) gets: 3x+3y=33

Divide both sides of the above equation by 3 to obtain: x+y=11 (3).

1)-(3) that is: x=4

2)-(3) that is: y=7

Therefore, it is necessary to use 4 A-shaped steel plates and 7 B-shaped steel plates.

Let block a x and block b y.

a→2c b→c

a→d b→2d

Column: 2x+y=15

x+2y=18

We get x=4 y=7

A 4 blocks B 7 blocks.

Set A-type steel plate X, B-type steel plate Y

2x+y=15

x+2y=18

The solution is x=4 and y=7

It's a mathematical tongue twister, two or three times when you can get around, and if you can't get around, you've been going around in circles, 90 degrees-(

If the unit price of raw material A is 2x, the unit price of raw material B is 3x

Equivalent relationship: 1. The weight of raw materials of A + the weight of raw materials B = the weight after mixing 2, the ** of A before mixing + the ** of B = the total after mixing**Comprehensive relationship: the weight of raw materials of A + the weight of raw materials of B = after mixing** The unit price after mixing is 2000 2x+1000 3x=(2000+1000) 9x=4 The unit price of A raw materials is 2x=8 yuan, and the unit price of B raw materials is 12 yuan.

Let the unit price of type A raw materials be 2x 3x type B

3000)÷ 2000/2x+1000/3x)=9

If the unit price of raw material A is 2x, and the unit price of raw material B is 3x, then there are 1000x raw material A and 3 1000x raw material B.

So 3000 (1000x+3 1000x)=9 will calculate the rest.

It seems like this (o)....

Solution: If the unit price of A is 2a yuan, then the unit price of B is 3a yuan.

Then: 2000 (2a) + 1000 (3a) = (2000 + 1000) 9

Solution: a=4.

Therefore, the unit price of A = 2a = 8 (yuan).

If you set the water level to 0, then the total water level is the sum of its parts.

Total water level = to normal water level).

You add up those changes in the water level, and what you end up with is the overall change in the water level. (m.)

This question mainly examines the understanding of positive and negative numbers, the change in water level in a week is the sum of positive and negative numbers, and the result is negative, indicating that the water level is lower than normal in a week, and positive is the opposite answer.

That's not what you do, right?

The change on the first day is = down Just take a positive number and 0 is the normal water level.

The baseline water level for the second day is so the change for the second day is to this section which is equal to the third day is - to equal to the fourth day, and so on.

Day 5 and Day 6.

The sum of the seventh day gives the total amount of water level change as .

If you want to use the formula, it is [ + is omitted after the braces represent the absolute value, and then the change from the third day to the fourth day is a negative value and a positive value is used The normal water level is 0 under the transition is +(0+

If you set the water level to 0, then the change in the total water level is the sum of their sums, if it is positive, it means that the water has risen, if it is negative, it means that it has fallen, and the total water level = the normal water level has risen).

The calculation process is based on the law of addition of rational numbers.

Solution: According to the title, ==

As a result, the overall change in the water level of the reservoir during the week is one metre above the normal water level.

。-13。-1 to the power of 3 6

4。is an integer.

to the 3rd power.

Each school gets money in Nm

So n m 4 1 m

Because m≠0, 4m 1 n

After the first school gave 4 1 m, the remaining n 4 1 m 4 m 3 1 m so the second school should get (4 m 3 1 m) 1 m 8 n m 4 1 m

i.e. (4m 4 1 m) 1 m 4 0

i.e. 8 4 m 1 m 2 0

So 1 m [4 (4 4 4 8)] 2) (4 4 3) (2) -2 2 3

Because m is a positive number, m -2 2 3

m is not an integer, and the problem is wrong.

I don't think it's right, what it refers to is what is left to get rid of.

I can't figure it out, and the question should be wrong.