Math problems are urgent

Solution: If there are x people in class A, then there are (115-x) people in class B.

1 3x*10+2 3x*5+[2 5(115-x)]*10+[3 5(115-x)]*5=total donation.

10 3x+10 3x+(46-2 5x)*10+(69-3 5x)*5=total donation.

20 3x+460-4x+345-3x = total donation.

20 3x+805-7x = total donation.

805-1 3x = total donation.

If there are x people in class A, then there are (115-x) people in class B and the total number of people is y

y=1/3*10*x+2/3*5*x+(115-x)*2/5*10+(115-x)*3/5*5

y=20/3*x+7*(115-x)=805-1/3*x

1/3*x*10.+(115-x)*2/5*10+2/3x*5+.+115-x)*3 5*5=Total money.

805-1 3x = total money.

Donation for Class A: 1 3*x*10+(1-1 3)*x*5 Donation for Class B: 2 5*(115-x)*10+(1-2 5)*(115-x)*5

Total = 1 3 * x * 10 + 2 5 * (115-x) * 10 + 5 * (2 3 * x + 3 5 * (115-x)).

20/3x+7(115-x)

805-1/3x

If the slowest player is x, the fastest is 6 5x, and if the slowest rider rides ym, the fastest is y+7000

35x=yy+7000=6/5x *35

x=1000 points.

6 stools: 5x = 1200 points, 1200 points for fast ones, 1000 points for slow ones.

The ratio of boys to girls is 5:6

The total number of people must be a multiple of (5+6), that is, a multiple of 11 The total number of people who meet the meaning of the question is only 11*4=44 people.

There are 44 boys 11 * 5 = 20 people.

There are 44 girls 11 * 6 = 24 people.

Male: Female = 5:6, indicating that the total number of people is a multiple of 11, and it can be seen that there are 44 people, 20 boys and 24 girls.

5+6=11

Because between 40 and 50.

So it's 44 boys, 20 girls, and 24

Let's start with a simple look.

In the third question, the number 9 is the square of 3, and in the multiplication formula, it is also three three to get nine, we can easily think that four integers that are not equal to each other must have positive and negative, which is 9 = -3x -3 =(-1 x3)x(1x -3) = -1 x3 x1 x -3, among the four numbers, 1 and -1, 3 and -3, both are opposites, and the sum of the four numbers is only 0.

In the second question, it's better to change the symbol when you calculate it yourself. a*b = 4ab, e.g. 2*6= 4x2x6= 8x6= 48, so that 3*5 is 4x3x5 =3x20 =60

The first question, the monthly salary is 2500, of which 1600 is exempt from tax, and the tax needs to be paid, that is, 2500 -1600 = 900 yuan, and this 900 is divided into two according to 500, and there are 400 yuan for those who exceed 500, so that 500 yuan is calculated according to 5% and the tax rate, and the last 400 yuan is calculated according to the 10% tax rate. Look.

500x 5% +400x 10% = 5x5 + 4x10 = 25 +40 = 65

The monthly personal income tax is 65 yuan, do you understand?

, a, b, c, d are four integers that are not equal to each other, and if abcd=9, then the value of a+b+c+d is 0

Question 1: (2500-1600-500) 10%=40 (yuan)40+500 5%=65 (yuan) Answer: Xiaoliang's father has to pay 65 yuan of personal income tax every month.

Question 2: 3*5=4*3*5=60 Answer: The value is 60

Question 3: The four numbers are 1, -1, 3, -3, so 1+(-1)+3+(-3)=0 Answer: a+b+c+d is 0

4 5 for all parts is 180 divided by 5 8 equals 288, then all parts are 288 divided by 4 5 equals 360

180 divided by 5 8 = 288 (pcs) 288 divided by 4 5 = 360 pcs

Don't blame me for being wrong, this should be elementary school knowledge I've almost forgotten it

1) EF2) EF=BE+DF, follow the prompts to prove two congruences.

From the correct A, it can be seen that bringing x=2, y=-1 into cx-4y=10 gives c=3.

B is wrong: x=10 17,y=-4 5 is brought into cx-4y=10, and it is mistaken as c=(66*17) 50.

Bringing x = 10 17, y = -4 5 into ax + by=1 and cx - 4y = 10 gives x = (10b + 4) (4a + bc) = 10 17. ①

Bring x=2,y=-1 into ax+by=1 to get 2a-b=1. Bringing c=(66*17) 50 into the re-synthesis, we can calculate the values of a and b.

Substituting x=2,y=-1 into cx-4y=10 gives 2c+4=10, and the solution gives c=3

Substituting x=2, y=-1 into ax+by=1, and substituting x=10 17, y=-4 5 into ax+by=1 to get the system of equations.

2a-b=1,10/17)*a-(4/5)*b=1

Here's the answer:

Substituting x=2 and y=-1 into the original equation is obtained.

2a-b=1①

2c+4=10*****====>c=3

Substituting x=10 17, y=-4 5 into equation (1) gives 10 17a-4 5b=1

Simultaneous can solve the values of a and b.

Section A is correct, so bring x=2, y=-1 into the solution to get c=3,,,2a+3b=1, and because B is wrong about c, so bring x=10 17, y=-4 5 into the first equation to solve.

a=38/37 b=-13/37

So the speed of the sound is big.

The first formula of the landlord Lao Hong, m 2 (a-2) + m (a-2) = (m 2 + m) (a-2) = m (m + 1) (a-2).

The second (x-y)(-y-x)=-x-y)(x+y)=y 2-x 2

The third 4x=5ySo we get x=5 4y with the servant dan into the formula (x 2-y 2) Chi Feng y 2=9y 2 16y 2=9 16

1、m²（a-2）+m(a-2)

m slip + m) (a-2).

2、(x-y)(-y-x)

x-y)(x+y)

x²-y²)

y-x volts are good.

3. If 4x=5y, then xy=5 4, so xy lacks lead = 25 16

x²-y²)/y²=(x²/y²)-1=(25/16)-1=9/16

1. Original formula = m(a-2)(m+1).

2. The original search tong formula = -xy-x +2y+xy=-x +y x=5yx=5y ridge leakage seepage cherry ridge 4

Original = [(5y 4) -y ] y = 9 16