The first application problem of binary linear equations is urgent

A and B factories originally planned to produce a total of 360 parts last month, but A completed 112 of the plan, B completed the plan of 110, and the two factories produced 400 parts.

Solution: Plant A originally planned to produce x units, and factory B originally planned to produce 360 x units.

112%x＋（360－x）×110%＝400

X 200 B factory was originally planned to be produced:

360 200 160 (units).

Factory A over-production:

200 112% 200 24 (sets).

Factory B over-production:

160 110% 160 16 (sets).

The midline of an isosceles triangle divides its circumference into two parts, 15 cm and 6 cm, and finds the length of each side of the triangle.

Analysis: Note that the isosceles triangle has two equal sides, and the midline on one waist divides its waist into two equal segments. Since it is not specified in the question which segment is 15 cm and which is 6 cm, it needs to be discussed separately.

Solution: Let the waist length be xcm and the bottom edge be ycm, that is, ab=x, then ad=cd= x, bc=y

If x+x=6, then y+x=15

x+x=6 yields x=4Substituting x=4 into y+x=15 gives y=13

Because 4+4<13, it cannot form a triangle.

2) If x+ x=15, then y+ x=6

x+x=15 gives x=10Substituting x=10 into y+x=15 gives y=1

10+1>10 is in line with the topic, so the three sides of the triangle are 10cm, 10cm, and 1cm

Set X for A and Y for B.

x+y=360

112%x+110%y=400。Well, the calculations will do it.

Summary. Solution: Let the number of boys be x and the number of girls be y.

If each boy digs an average of 3 tree pits per day, x boys can dig 3x tree pits per day; If each girl plants an average of 7 trees per day, then Y girls can plant 7y trees per day. Since only one tree needs to be planted per tree pit, there is 3x=7y. And because the total number of people is 340, then there is x+y=340.

Substituting 3x=7y into the above equation gives x+3x 7=340, simplifying to get x=140 4=35, and then bringing in x+y=340 to solve y=305. So there are 35 boys and 305 girls.

Thank you. Solution: Let the number of boys be x and the number of girls be y.

Each male filial piety student digs an average of 3 tree pits per day, so x boys can dig 3x tree pits per day; Each girl plants an average of 7 trees per day, so Y girls can plant 7y trees per day. Since only one tree needs to be planted per tree pit, there is 3x=7y. And because the total number of people is 340, then there is x+y=340.

Substituting 3x=7y into the above equation gives x+3x 7=340, simplifying to get x=140 4=35, and then bringing in x+y=340 to solve y=305. So there are 35 boys and 305 girls.

Do you understand? Understandable.

That's good.

Set up x pieces of $1 coins.

5 dimes y coins.

1 dime is hidden as a 15-x-y coin.

10x+5y+15-x-y=70

9x+4y=55

5x+4x+4y=55

4(x+y)=5(11-x)

Since x and y are both natural numbers, 11-x is a multiple of 4.

When x 7, y burner weighs -2 and is rounded.

When land slip x 3, y 7

So 3 pieces of 1 yuan coin, 7 pieces of 5 jiao coins, and 5 pieces of 1 yuan coin.

Let x,y,15-x-y (and 0<=x,y<=15 integers) x+5y+10(15-x-y)=70

Sorted out. 9x+5y=80

If you can get a multiple of five from 5 mausoleums, then it must be an integer ending in 0 or 5.

Therefore, the ruler laughs at the brigade x = 5, y = 7 (hypothetical method, and try out the liter pants).

Solution: Let win x draw y lose Zheng Ma town z field, x, y, z are all positive integers less than 12, from the meaning of the question, 3x+y=19

x+y+z=12

For the indefinite party to shout rough range, there are multiple groups of solutions).

The solution is x=6, y=1, z=5

Or. x=5,y=4,z=3

Or. x=4,y=7,z=1

w = respectively substitute the model spring into the above solution, can be obtained.

When x=4, y=7, z=1, w max.

1.Solution: If this person holds X shares A and B Y, then it is derived from the title.

solution, we get x=1000, y=1500

2.Solution: Let win x draw y lose z field, x, y, z are all positive integers less than 12, from the meaning of the question, 3x+y=19

x+y+z=12

In order to clear and correct Wang's indefinite equations, there are multiple sets of solutions).

The solution is x=6, y=1, z=5

Or. x=5,y=4,z=3

Or. x=4,y=7,z=1

w = substituting the above answer to the solution, which can be obtained.

When x=4, y=7, z=1, w max.

There are 30 questions here, I don't know if you can use them, these questions are followed by the answers, I hope you read them.

Set the number of students to x, because it is impossible for me to send ** to myself, so everyone sent (x-1) **, so x people sent x(x-1) **.

If you don't understand, please contact me.

In a party activity, each student presented a ** to other students, and a total of 90 ** were given away in this activity, so how many students are in this group?

Solution: There are x number of students.

Each student receives x-1 photo.

There are x students in total.

Then the total = the number of students The number of photos each student receives.

Columnar x(x-1) = 90

x²-x-90=0

x-10）（x+9）=0

x = 10 or -9 (rounded).

Then there are 10 students.

Solution: Suppose the number of students is x

Because everyone in the class is to be given a **, the number of ** sent by each person is x-1, so the number of ** sent by the class is x(x-1)=90

x^2-x-90=0

x-10)(x+9)=0

x=-9 (rounded up cannot be negative).

x=10 (person).

A: There are 10 students in this group.

If you are one of them, then you give everyone else a total of x-1 sheets**, then everyone is the same as you, a total of x people, so x(x-1)=90

Solution: Let the train length be x and the bridge length be y

According to the question: (x+y) 20=30

y-x)/20=20

x = 100 (meters).

y=500 (meters).

A: The bridge is 500 meters long and the train is 100 meters long.

There will be a sense of accomplishment when you think for yourself.

(1) Set the vehicle x, the number of people y 60 (x-1) = y --1).

45x+15=y---2)

2) After solving x,y, compare the magnitude of 220x with 300 (x-1) to draw conclusions.