Help me solve math problems, math problems help me solve them

3 4 in village B is equal to 2 3 in village A, then A: B is:

And because of 3:1 9:3, the ratio of A to C is 9:3, that is, the ratio of A, B, and C is 9:8:3

So the three villages each repaired:

A: 1000 9 (9 8 3) 450 (m) B: 1000 8 (9 8 3) 400 (m) C: 1000 3 (9 8 3) 150 (m).

At most, there is only one, and probably none!!

Because of the horn aob

The triangle of the angle AOC angle BOC adds up to 360°, the acute angle is less than 90°, and the three are acute angles, then, the sum of them is less than.

270°；If there are two acute angles, the sum of these two angles is less than 180°, and the third angle is greater than 180°, which is obviously impossible; So, it's mine.

The result!!

This is a ternary equation problem.

Let A repair a meter, B should repair B meter, and C should repair C meter.

Columnable Equations:

a/c=3/1 ①

3/4b=2/3a ②

a+b+c=1000 ③

C=1 3a is obtained by , b = 8 9a, and substituted by solution a=450, substituted

The solution is b=150 c=400

So A is 450 km, B is 150 km, and C is 400 km.

Add a minus sign, and the rest is not.

It is also possible to leave it unadded, and the rest is added with a negative sign.

The third question is not easy to do if you can't see the diagram.

Set up X km for repair, Y km for B, and Z km for C.

x+y+z=1000

x/z=33/4y=2/3x

Solution x=y=

Knowing that the perimeter of the sector is 10, find the relationship between the radius r of the sector and the area s, and find the maximum value of the area of the sector.

Solution: The perimeter of the sector = 2x the radius of the sector r + the arc length of the sector.

The calculation yields the following results: sector arc length = 10-2r

The ratio of the arc length of the sector to the circumference of the circle is the ratio of the central angle of the sector to 360 degrees, that is, the ratio of the sector area s to the area of the circle.

So sector area s: circle area = sector area s: pi xr squared = sector arc length: circumference = (10-2r): 2x pi xr

Simplification: The sector area s = [pi x r square x (10-2r)] 2 x pi x r = rx(5-r) = 5r - r squared.

The sector area s=5r-r squared is a quadratic function, the image is a symmetrical figure with the opening downward, and when r takes the value corresponding to the symmetry axis, s obtains the maximum value.

Therefore, when r = -5 [(1)x2]=5 2, the sector area s maximum=5x(5 2)-(5 2)x(5 2)=25 4

Factory A: (x>=500).

Factory B: (x>=500

If 1100 copies need to be printed, then:

The cost of the first plant: yuan.

The cost of choosing factory B: yuan.

Therefore, it is cost-effective to choose a factory.

If 1500 copies are printed, then:

The cost of the first plant: yuan.

The cost of choosing factory B: yuan.

Therefore, it is cost-effective to choose factory B.

（1+x）²=

1+x=x=2, according to the title, the height of the box is 4 cm, and the original side length is xcm, then the bottom side length of the box is x-8 cm.

x-8）×（x-8）×4=400

x-8）²=100

x-8=10 x=18

3. Set the width of the path to be x meters. The length of the rectangle enclosed by a small road is 20+2x meters. The width is 15+2x meters.

then (20+2x) (15+2x)=20 15+246(x-3) (x+41)=0

x = 3 meters. 4. (1) Let the side length of the first square be xcm and the second side be ycm, then x + y = 100, 4x + 4y = 56

Solve the equation to get x=6, y=8

2) Let the side length of the first square be xcm and the second side be ycm, then x + y = 196, 4x + 4y = 56

Solve the equation to get x=14, y=0

Therefore, it is concluded that such 2 squares cannot be cut.

3) Because the maximum square area that can be enclosed by this wire is (56 4) = 196, the sum of 200cm cannot be obtained.

5. If the canal is dug xm wide, the total area of the canal is.

92x+60x+60x-2x, then:

92 60-885 6=92x+60x+60x-2x x=1 or x=105 (not in accordance with the topic, rounded).

Therefore, the canal should be dug 1 meter wide.

Ask for x yourself

100 = 10 * 10 side length = 10 + 4 + 4 = 183The road width is x, (20+2x)*(15+2x)=20*15+246

4.Let one side be x, x 2+((56-4x) 4) 2=100 Second, the third question is to change 100 to find x

5.Set the width to x, 60x*2+92*x-2*x 2=92*60-885 and give points!

1.199 divided by 199 and 199/200 (simplified).

199 and 199/200 199

199 199 + 199 199/200

1+1/200.

201/200

So 199 divided by 199 and 199/200 = 200/201

2.1 and 2/2 + 1/6 + 3 and 1/12 + 4 and 1/20 +.20 and 1/420 (short-term).

Original = 1 + 2 + 3 + .19+20+1/2+1/6+..1/420

210 and 21/21

3.There are three numbers A, B and C, the ratio of the number A to the number B is 3:4, the ratio of the number B to the number C is 4:7, and the sum of the numbers B and C is known to be 66, find the number of A.

Number A: Number B = 3:4

Number B: Number C = 4:7

i.e. A:B:C = 3:4:7

A number: 3*66 (4+7)=18

4.Two two-digit numbers, their greatest common factor is 6, and the least common multiple is 126, what are these two numbers?

So the numbers are 18 and 42 respectively

5.Of the group of tourists, 3 out of 4 know French, 4 out of 5 know English, 13 out of 20 know both languages, and another 10 do not know both languages.

6.Blue Sky Technology organized employees to go rowing, and they calculated that if one boat was added, there would be exactly 6 people in each boat. If you reduce the number of boats by 1, you will be able to seat exactly 9 people per boat. Ask how many employees of Blue Sky Technology participated in the boating event.

Boats: 9*(1+1) (9-6)-1=5.

Number of people: 9*(5-1)=36 or 6(5+1)=36.

Note: I'm just a primary school student, don't make it too complicated for my brother and sister, use the easiest way to solve thank you.

1.Solution: 199 199 and 199 200

2.Solution 1 1 2 + 2 1 6 + 3 1 12 + 4 1 20 +...20 and 1 420

210 20 21 (210 21/21).

3.The ratio of the number B to the number C is 4:7, and the sum of the numbers B and C is 66, so.

The number B is 66 4 (4+7) = 24

And the ratio of the number A to the number B is 3:4, so.

The number A is 24 3 4 = 18

4.Solution 126 = 6 21 = 6 3 7

So these two numbers are 6 3=18 and 6 7=42

5.(4 out of 3 people know French wrong, it should be 3 out of 4).

The number of passengers in this group is 10 (1-(3 4+4 5-13 20)) = 100 (people).

6.When there are 6 people in each boat, 2 more boats are used than when there are 9 people in each boat, and the number of people in these two boats is 6 2=12 (people).

This means that if each boat seats 9-6=3 more (people), you can seat 12 more people.

So, the number of ships at this time is 12 3=4 (strips).

So the number of employees is 4 9 = 36 (people).

What grade are you? I'm also just an elementary school student, and I'm only in the fourth grade. I can't even understand some of your questions.

1.199 divided by 199 and 199/200 (simplified) = 199 divided by (199x200+199) 200 = 199x200 199 (200 + 1) = 200 201

I'll just write the answers. 199/201210 and 69/70The number of A is 1818 and people. 36 people.

199 199 and 199 200

1 1 2 2 1 6 3 1 12 4 1 20 ......20 and 1 420

210 and 20 21

A: One number is 18 and one number is 42.

Of the group of tourists, 4 out of 3 know French, 4 out of 5 know English, 13 out of 20 know both languages, and another 10 do not know both languages. (The question may be incorrect, if 3 out of 4 people know French.......)）

A: There are 100 tourists in this group.

or (5 1) 9 36].

A: Blue Sky Technology has 36 employees participating in the boating event.

Solution: Divide by 199 and 199/200 = 199 divided by 199 + 199 divided by 199/200

1/2 + 2 and 1/6 + 3 and 1/12 + 4 and 1/20 +. 1/20 and 420

10x21+[(1--1/2)+(1/2--1/3)+(1/3--1/4)+(1/4--1/5)+.1/20--1/21)]

210 and 21/21

3。From the meaning of the title, the ratio of the three numbers A, B, and C is 3:4:7, because the sum of the numbers B and C is 66, so the number A is: 66 divided by (4+7) multiplied by 3=18.

4。Since 126 = 6x3x7, the two two-digit numbers are 18.

5。Is it possible that the title is incorrect: "4 out of 3 of the tourists in a group"?

6。X number of employees participated in the boating event.

According to the title: x 6 = x 9 + 1

Solution: x=18

A: Blue Sky Technology has 18 employees participating in the boating event.

Solution: Set my sister's original x yuan. Because the sisters have the same amount of money, x = sister's money.

Lift land x+90=7(x-90).

x+90=7x-630

x-7x=-630-90

6x=-720

Zheng answers, stupid x=-720 -6

x=120 A: My sister originally had 120 yuan.

2.Solution: Let's run home at a speed of 80 meters per minute and get the math book for x points.

80x=60*4

x=3Because it took a total of 15 minutes to go to school, it takes 15-3-4=8 (points) to run back to school at a speed of 80 meters per minute

80*8=640 (m).

A: Xiaohua's home is 640 meters away from the school.

If you don't understand, continue to ask.

1) Solution: Set the original x yuan for the younger sister.

x+90=7(x-90)

Solution: x=120

Answer: My sister originally had 120 yuan.

2) Old dismantling: Set Xiaohua is x meters away from the school.

4 times 60 + x = 80 times 11

Solution: x=640

Answer: Sun Ru Xiaohua is 640 meters away from the school.

Hope it helps! Hope!

Question 1: x+90=7 (x-90).

Question 2. 4*60+x=80*11

The answer is 640

This kind of problem is to find the least common multiple of length and width.

So the least common multiple of 24 and 18 is 2*2*2*3*3=72 cm, so the side length of the square is 72 cm.

3 bricks on one side of the 24-long paving, and 4 bricks on the 18-sided side. A total of 3*4=12 bricks is required.

The least common multiple of 24 and 18 is 72, so the square is at least 72 cm long, and 12 bricks are required.

(1) The unit price of a certain high-quality wall paint is 240 yuan per barrel, which can paint 50 square meters of walls or roofs. There are three rooms of the same shape and size, each one meters long, wide and high. How much does it cost to buy a topcoat to paint the roof and walls of three rooms (excluding the 12 square meters of doors and windows in each room) with this lacquer?

1.The area is (2*.)

2.To buy barrels (more than seven barrels is 8 barrels).

3.It costs a total of 8 * 240 = 1920 yuan.

2) Xiao Wang read a book, read it for three days, and there were 102 pages left. If you look at it at this rate for four days, you are left with two-elevenths of the whole book, how many pages is there in the book?

1.I read 1-2 11 = 9 11 in four days

2.Watch 9 44 a day

3.I watched 27 44 in the first three days, and 17 44 remained

4.There are 102 divided by 17 44 = 264 pages.

3) Three-sevenths of the number A is nine-eleventh of the number B, the number C is half of the number A, and the number B is 2 times greater than the number C, so what is the number B?

1B = 3 7 divided by 9 11 = 11 21 times A.

2.C = 1 2A.

3.B minus C = 1 42 A = 2

4.A = 84, B = 44, C = 42

4) Fill two cylindrical containers with inner diameters of 20 cm and 30 cm respectively and a height of 40 cm with water, and then introduce the water of both containers into a cylindrical container with an inner diameter of 50 cm and a height of 60 cm, how many centimeters is the height of the water surface?

1.The two radii are 10 cm and 15 cm, and the volume is 4000 and 9000 for a total of 13000

2.The bottom area of the imported container is 625 square centimeters, and the water surface height is 13000 divided by 625 = 20 centimeters.