Help solve four math problems, equations and equations.

Parallelogram area = base height.

Trapezoidal area = 9 height 2 = height.

The ratio of area = 3:2, that is, height: bottom height = 3:2, so the bottom = 3cm set the second pile of original x tons.

120×（1-1/4）：x × 3/5=3：590×5=9x/5

x = 250 tons.

If the model aircraft team is x people, the mathematics team will be x+3 people, and the meteorological team will have (4 3) x people.

According to the ratio of the number of students in the mathematics group to the total number of the three groups is 1:3, x+3): [x+x+3+(4 3)x] = 1:3

10/3)x+3=3x+9

1/3)x=6

x=18 so there are 18 model aircraft, 21 math and 24 meteorology.

38/56=(a/7)+(b/8)

General score: 38 56 = (8a 56) + (7b 56) 38 = 8a + 7b

a, b are natural numbers, then a is in the range of 1 to 4, and b is in the range of 1 to 5, respectively.

When a=1,2,4, b has no solution.

a=3,b=2

So a=3, b=2

If the height is h, the trapezoidal area s= then the parallelogram area is 3h, and the base can be obtained according to the parallelogram area formula

From the meaning of the title, the remaining part of the first pile is 120*3 4=90, then the remaining part of the second pile is 90*5 3=150, and then according to the remaining 3 5 of the second pile, we can get 150 3*5=250

Let the equation ternary equation be math x meteorology y y model airplane z to get the equation:

3x=x+y+z y z=4 3 x-z=3 Solving the equation gives z=18 x=21 y=24

Get 8a+7b=38 when a=1 b is not a natural number, when a=2 b is not a natural number, when a=3 b=2, when a=4 b is not a natural number, and finally get 5

If the bottom is x, and the height is h, then there is 9h 2xh=3 2

Solve to get x=3

Pure hand-played.

2. Let the divisor be the pre-trapped simple x, then the dividend is 8x+9, x+8x+9+8=206x=21

Let x hours elapse, then.

x = set the right hand ruler to read x seeds.

3x-12=x

x=6 So there are 6 smart pants in the right hand and 18 in the left hand.

1.Because the square of equation (a-2)x + ax+3=0 is a unary equation, the square term is 0, i.e., a-2= the equation becomes 2x+3=0The solution is x=-3 2

2.From the meaning of the question, the solution of 3a+2x=15 is x=3, and after substitution, there is 3a+6=15 to solve a=3, so the original equation is 3*3-2x=15, that is, -2x=6, and the solution is x=-3

3.There are x households, and it can be seen from the title that the number of visits to each household is 2, that is, 2x should be visited, and it is known that the households at the 2nd end of the street can only visit one, so the equation is 2x-2=54, and the solution is x=28

4.If the small tractor cultivates x mu per hour, then the large tractor cultivates per mu per hour, and x+ solves x=12 according to the topic

1. Encounter problems.

Let us meet after x hours, 65x+72x=274

137x=274

x=22, the unit price of the ballpoint pen is x yuan, then the unit price of the fountain pen is 4x yuan 4x+5x=

9x=x=pens4x=4*

3. Set up team B to repair x meters every day, and team A to repair 2x meters per day, x + 2x) * 8 = 4230

3x=x= (Team B).

4.Set A to save x yuan and B to save y yuan.

x+y=1000

x-240=3(y+80)

Solving the system of equations yields x=870

y=130 or let A save x yuan, B save (1000-x) yuan.

x-240=3(1000-x+80)

x-240=3000-3x+240

x=8701000-x=1000-870=130 (B).

1.Does the question mean that the two cars depart from Nanjing and Shanghai respectively? If yes, the equation is as follows:

65+72）*x=274

The solution is x=22Let the ** of the ballpoint pen be x yuan, then the ** of the fountain pen is 4x5x+4x=

9x=x= 4x= of the fountain pen

3.Set up team B to repair x meters every day, which can be seen from the title.

x+2x)*8=4230

3x=x=4.Set A to save x yuan and B to save y yuan.

x-240=y+80

x+y=1000

The solution is x=660

y=340

1.(65+72)x=274, x=2km2Ballpoint pen** x 4x+5x=yuan x= fountain pen 4x= yuan3(x+2x)8=4230 x= meter dollars.

1 If the number of tens is x, then the number of hundreds is 2x+1, and the number of single digits is 3x-1100(3x-1)+10x+(2x+1) [100(2x+1)+10x+3x-1]=99

Do you solve it yourself).

2. If the top is xm, then the bottom is (600-x)m2x=(600-x)*3

If the solution is x=360, the bottom is 240m

3 Solution: If A and B are entered If A and C are x, B is 50-x A is x, C is 50-x B is x, then C is 50-x

The solution is x=25, and B is 50-x=25 The solution is x=35, then C is 50-x=15 This scheme is not possible.

150 * 25 + 25 * 200 = 8750 yuan.

150 * 35 + 250 * 15 = 9000 yuan, so the selection of A is 35, C is 154, and the whole process of solving is x

x (x solution gives x=80.)

Average speed = (80+80) (km/h.)

Plagiarism is prohibited!!

1.Solution: Let this number be x

20xjia10xjia3xjian1

1. There are x boys and y girls.

x+y=170

3x=7y gives x=119, y=51

2. Make tops x people, make pants y people.

x+y=54

8x=10y

x=30 y=24

3. Set up x people for the production of bolts and Y people for the production of nuts.

x+y=28,12x=18y*2

x=7,y=21

4. Set the age of the uncle to be x and the age of Xiaogang to y

y-(x-y)=4

x+(x-y)=37

x=26, y=15

1. Set up another car to travel x kilometers per hour.

350/(45+x)=

x=552, let the B ship travel x kilometers per hour.

1172-26*2)/(26+x)=25x=

3. Let its bottom be x decimeter long.

3+x)*10/2=40x=5

1.Suppose another car travels x kilometers per hour.

then (45+x).

x=552.Let the B boat travel x kilometers per hour.

26*2+(26+x)25=1172

3.Set the bottom length x decimeter.

3+x)*10/2=40x=5