Solving Problem Problems with Equations!!! Speed, hurry, four !!

1.Let the drop be x cm, then:

15*15*x=20*15*10；

x=40/3

Dropped by 40, 3 cm.

2.If the length is x meters, then x < 14 meters, according to the title:

x+2(x-5)=35;

3x=45;

x=15;15>14, not compliant;

If the length is 14 meters, the width = 14-5 = 9 meters, and the s = 9 * 14 = 126 m 3Let the drop be xcm, then there is:

20*x=2*2*2=8；

x=；So it fell by centimeters.

4.Set the height to x meters, then there is:

5*3*60+2(5x+3x)*60*(2/3)=1860;

900+16x*40=1860;

640x=960;

x = tank height of 1,. 5 meters.

15*15*x=20*15*10

x = 200 15 = 40 3 cm.

Reasonable, length = 14, width = 14-5 = 9

Area = 126 square meters.

The height is reduced by 2*2*2 20 = cm.

High = (1860-3*5*60) [40*2*(5+3)]=

2. If the width is x meters, the length is x+5

If possible, there is 2x+x+5=35

The solution is x=10, then the length is 10+5=15 meters, which is beyond the length of the wall, so the above method is not feasible.

The length can be 13 meters, then the width is 11 meters, and the area is 13*11=143 square meters.

1. Solution: Set up a two-point shot x ball, and a free throw Y ball.

2x+y+3*3=28

3+x+y=14

Solution: x=8

y=3A: Jordan made 8 two-point shots and 3 free throws.

2. Solution: The original plan was to produce x parts per hour.

26x=24*（x+5）-60

Solution x=30

26*30=780 (pcs)

A: It was originally planned to produce 780 parts.

3. Solution: Set up x rooms in the dormitory.

8x+12=9*（x-2）

Solution x=30

8*30+12=252 (person).

A: This school has 252 students and 30 dormitories.

Purely handmade...

1.x on x on two shots and 14-3-x on free throws.

2x+14-3-x+3*3=28

x=8 made 8 of 2-pointers and 3 of free throws.

2.Originally planned to produce x pieces per hour, the original plan was to produce 26x pieces.

24(x+5)-60=26x

x=60, so it was planned to produce 1560 pieces.

3.There are x rooms in the dormitory, and the accommodation is 8x+12 people.

8x+12=9（x-2）

x=30 so 252 people in accommodation and 30 dormitories.

If the price is reduced by x yuan, the profit of each piece is 50-x yuan, and the number of saleable pieces is (30 + 3x) (50-x) (30 + 3x) = 2400

solution, x = 30 or 10

Because x 50 , 30+3x 0

So 50 x -10

So the price is reduced by $10 or $30.

I don't know if you're asking how much the mall is making a profit of 2,400 yuan per day and how much the price of clothes is reduced

The passenger ship and the cargo ship departed from ports A and B at the same time, and the passenger ship and the freighter met six hours later, but they were still 6 kilometers away from the midpoint of the two ports. The speed of a passenger ship in still water is known to be 30 kilometers per hour, and the speed of a cargo ship in still water is 24 kilometers per hour. Find what is the velocity of the water flow?

Solution: Let the water flow velocity be x kilometers per hour.

6（30-x）-6（24+x）=6×2

180-6x-144-6x=12

12x=24

x=2A: The speed of the water is 2 km/h.

Suppose the ** of the chair is x-yuan.

Then the ** of the table is x+30 yuan.

Columnable equations.

6（x+30）=9x

6x+180=9x

3x=180

The ** of x=60 chair is 60 yuan.

Buy all chairs.

You can buy 720 60 = 12 handfuls.

The ** of the table is 60 + 30 = 90 yuan.

Buy all the tables.

You can buy 720 90 = 8 sheets.

Let the minimum number be x, then the other numbers are x+1, x+7, x+8

x+x+1+x+7+x+8=44

4x+16=44

4x=28x=7A: 7, 8, 14, 15 respectively

Let the single digit x, then the ten digit is 3x

From the meaning of the question: 3x 10+x=(x 10+3x)+54: x=3

3x=9, so the original number is 93

Solve the number on the single digit as x

10x×3+x-54=10x+3x

31x-54=13x

18x=54

x=3, so the original number is 93

Set the annual interest rate for one-year fixed storage at x

Interest = 5000*x

Interest tax = 5000 * x * 20%.

Sum of Ben and Profit = 5000 (1+x).

Therefore, according to the title: the sum of take-home principal and interest after deducting interest tax is 5080 yuan, that is, 5000 (1+x) - 5000 * x * 20% = 5080, that is, 80% * 5000 * x = 80

x = i.e. annual interest rate for one-year fixed storage = 16%.

Set the annual interest rate for one-year fixed storage at x

Then 5000(1+x%) 5000*x%*20% =5080

Just solve the equation, I hope you can do the rest by yourself.