Please help me with a math equation problem for junior high school

Type A uses 3 rectangular iron sheets and 2 square iron sheets.

Type B uses 4 rectangular iron plates and 1 square iron plate.

Let type A be x and type B be y.

There is 3x+4y=212

2x+ y=88

Solution: x=28, y=32

A box area = 10 * 10 * 2 + 20 * 10 * 2 + 20 * 10 = 800 B box area = 20 * 10 * 2 + 20 * 10 * 2 + 10 * 10 = 900 total area of iron sheet = 212 * 20 * 10 + 88 * 10 * 10 = 51200 set A box x, B box Y.

Then: 800x+900y=51200

8x+9y=512

8(x-1)=9(56-y)

So: x-1=9m (m is a non-negative integer).

x=1+9m

y=56-8m

So, there can be the following solutions:

x=1, y=56

x=8, y=48

x=19, y=40

x=28, y=32

x=37, y=24

x=46, y=16

x=55, y=8

x=64, y=0

Solution: Let type A be x and type B be y.

3x+4y=212

2x+ y=88

Solution: x=28, y=32

Answer: Type A uses 3 rectangular iron sheets and 2 square iron sheets.

Type B uses 4 rectangular iron plates and 1 square iron plate.

1.Solution: Set the value of the clothes x silver coins.

x+10)/12=(x+2)/7

7x+70=12x+24

5x=46x=A: This garment is worth a silver coin.

2.Solution: Set the price of the commodity to be X yuan, according to the title:

90%x-250）/250=

Solution: x=320

A: The list price of the product is 320 yuan.

1. If the value of the clothes is x silver coins, then:

x+10)÷12=(x+2)÷7

That is, 12 (x+2) = 7 (x+10).

That is, 12x+24=7x+70

5x=46x=2, set the list price to x, then:

x×90%=250×（1+

i.e. 90% x = 288

Get: x=320 (yuan).

That is, the price of this commodity is 320 yuan.

Profit margin = profit purchase price 100%.

1.Solution: Set the value of the clothes to x credits.

7（x+10）=12（x+2）

5x=46x=yuan).

Profit Margin = (List Price - Purchase Price) Purchase Price = Profit Purchase Price.

Cope: 10+ (5-3).

x=6A: The distance by car is 6 km.

1) If the distance is x, then the fee is paid.

2 Because y=15, if you bring in the above equation, then x=6km

Set the selling price to be x and the original purchase price to y

x-y)*Profit percentage is (x-y) y=80%.

Or set the profit percentage to x

x* finds 80% of the value of x

Seek x as the original price, and then seek profit.

Let the original purchase price be x and the selling price be y, (y-x)= solve the relationship between y and x, and use x to represent y, (y-x) y=?It's the original profit.

If the original purchase price is X yuan and the selling price is Y yuan, then the original profit is (y-x) yuan, and now the purchase price is reduced by 8%, that is.

The selling price remains the same, i.e. y

So the profit is.

Now the profit is 110 percent.

So y = and the original profit margin is the profit of the purchase price of 100%.

So (y-x) x 100%.

And y = so profit margin = (

So the profit is eighty percent.

Let the original purchase price be x, the selling price be y, and the original profit is a.

y-x=a*x

Solve a=I don't know if it's right or not, I hope it can help you.

Solution: Let the water velocity be xkm h

6(x+12)=10(12-x)

6x+72=120-10x

6x+10x=120-72

16x=48

x=3A: The water velocity is 3km h

Let the flow rate be v, according to the meaning of the question:

12+v)*6==(12-v)*10

The solution is v==3km h

The speed of the flow is 3 kilometers per hour.

Let the water velocity be x, and the distance between the two piers is y

10（12-x）=y

6（12+x）=y

x=3y=90

1. A city encourages residents to save water, and puts forward the following points for users: if the monthly water consumption does not exceed 2 tons, it will be charged at a yuan per ton, and if it exceeds 2 tons, it will be charged at 2a yuan per ton. If a resident charges $8a for water this month, ask the resident about his or her water consumption this month.

Suppose the resident's monthly water consumption is x tons.

2a+(x-2a)*2a=8a

x = 2a+3

2. A store on the same day ** two repeaters, the price is 60 yuan, one of them made a profit of 20%, and the other lost 20%, asking whether the store made a profit or a loss this time?

The original price of the first unit is 60 (1+20%)=50 yuan, and the original price of the second unit is 60 (1-20%)=75 yuan, and the original price of two units is 50+75=125 yuan.

Now it sells for 60*2=120 yuan.

Lost 125-120 = 5 yuan.

The first question is more than 2 tons, so the excess part is 7a tons, and the excess part uses water tons in total.

The second question is not to win or lose.

The total number of ninth-grade students in the school is x.

x-15)/30=(x+5)/40 +14x-60=3x+15+120

x=195

Solution: There are a total of students x pure mining. Do pure nuclear rule.

x=21A: There are 21 students in this gardening group.