Please help my son with some math problems, thank you!

6) Passenger cars and trucks travel in the same direction from A and B at the same time 4 hours later, the two cars are 120 kilometers apart After another 2 hours, the two cars are 120 kilometers apart Find the distance between A and B? - 120+120) 2*4+120=600 (km).

7) Two cars A and B travel in the same direction from two places at the same time, car A travels 24 kilometers per hour, car B travels 30 kilometers per hour, and the two cars meet at a distance of 18 kilometers from the midpoint How many kilometers are there between the two places? - 18*2 (30-24)=6 (hours); (30+24)*6=324 (km).

8) If you walk 60 meters per minute from home to work, you will be 2 minutes late; If you walk 80 meters per minute, you can get 3 minutes earlier If you ride a bicycle for 150 meters per minute, how many minutes does it take to get from home to work? —2+3) (1 60-1 80)=1200 (m); 1200 150 = 8 (minutes).

9) The math teacher lives on a side street, and the house numbers on the street are No. 1, No. 2, No. 3, 、......A student asked the math teacher what number he lived in, and the math teacher said, "Subtract the sum of the house numbers on the side street from the house number of my house and it is exactly 388, please do the math calculation, what is the house number of the math teacher's house?" —Involves the problem of summation of natural sequences.

1 to 27, and the sum is (1+27)*27 2=378;1 to 28, and is (1 + 28) * 28 2 = between these two numbers, so it is presumed that there are 28 households in this street. The math teacher's home is 406-388 = 18 (number).

10) The quotient of two numbers divided is 20, the remainder is 19, and the sum of the dividend, divisor, quotient and remainder is 1885, what is the divisor? - 1885-20-19-19) (20+1)=87, so the divisor is 87

Hehe, it's a bit of a back-to-basics feeling without equations, it's a bit interesting!

6.The speed of the two cars is V1 and V2 respectively, and the distance between the two places is x km.

Answer: x=(v1+v2)*4+120, and because the two cars are 120km apart after 4 hours, and the two cars are 120km apart after 2 hours, it means that the two cars meet after 1 hour at a distance of 120km, so (v1+v2)*1=120. So we get x=600km.

v2=30, let the two places be separated by s kilometers, and it took t hours for the two cars to meet:

Then, (v1+v2)t=s, (v2-v1)t=18*2, solution, s=324km

So we can get t=18 (minutes) and s=1200, if v=150, then t1=1200 150=8 minutes.

9.This problem is a binary linear equation with an infinite number of solutions. (You didn't make a mistake, it's not a question that elementary school students can solve).

10.Column equation: Let the dividend be a and the output be b, then.

a=20b+19, a+b+20+19=1885, a=1759 b=87

6.Solution: Let the two places be separated by x kilometers.

x-120) 4=(x 120) 6 6x-720=4x 480 2x=1200 x=600 A; (omitted) 7Solution: Set up two cars to walk for x hours.

2 (24 x 18) = 30 x 24 x 48 x 36 = 54 x 6 = 36 x = 6 6 (30 24) = 324 (km) Answer: (omitted).8.

Solution: Set up a home to the unit x meters. 6 x 60-2=x 80 3 8x=6x 2400 2x=2400 x=1200 1200 150=8 (points) A:

Omitted) 2 3 4....28 = 406 406-388 = 18 (number) Answer: (omitted) 10

Solution: Let the dividend x, the divisor y{x=20y 19(1) {x=1827(2) Substitute (1) into (2):

21y=1827 y=87 Answer: (omitted) (What a great opportunity for your son to learn equations!) I didn't understand anything about the binary equations I learned in my third grade, but I laid a good foundation for my future studies.

I'm now a great algebra student in my class).

6. Let the speed of the passenger car be x, the speed of the truck be y, and the distance between A and B z m is derived from the title:

The two cars were 120 meters apart after 2 hours, so they met 5 hours later.

So 4*(x+y)+120=z x+y=120z=6007 Let t meet after hours, and the distance between the two places is m meters. From the meaning of the title:

24t+30t=m 30t-18=m/2

The solution: t=6 m=324

8 T minutes away, s meters apart. From the meaning of the title:

60t+60*2=s 80t-80*3=s solution: t=18 s=1200

Then you want to ride a bicycle.

1200 150 = 8 (minutes).

9 It seems that the problem of this problem is missing some conditions, and even if there are conditions, it is a 2-yuan first-order equation, and your sons will not be able to do it.

10 Let the divisor be x and the dividend y be y, which is derived from the title:

y*20+19=x x+y+20+19=1885 solution: x=1759 y=87

6 Passenger speed x, cargo speed y, distance between two places z

4(x+y)+120=z 6(x+y)-120=z z=6007 Set the time t, the distance between the two places z

30-24)t=18*2 z=(24+30)t=3248 Let t be minutes, and the distance is s

s=60(t+2)=80(t-3) t=18 s=1200 The time required to ride a bicycle is s 150=8

9 Inadequate conditions.

10 is divided by x and by y

x-19=20y x+y+20+19=1885 a=1759 b=87

It's so stingy, so many questions are only 5 points, next time I want to have more!!

18 (30-24) = 3 (hours).

3 (24 30) 162 (km).

That's it.

Directly place a = -2

b = substitution is fine.

a * b = (-2)^2 - 2*(-2^3- 1)-1/==

Well, you just need to bring it in.

2) 2-(1 2)2-(2(-2 cubic -1*2) divided by (-2-1 2).

The answer is that I don't know if there is a mistake, just bring it in and use a calculator to calculate it, I don't know if your a2 is the square of a, I am like this.

-2-1/2-[2(-6-1)-2]/(-1)=

I've just done it right, give it points.

7 5, the result may be wrong, but the method is very simple, as long as a, b are substituted with -2, 1 2 respectively.

A: There are 500 new books in the school library.

It can also be solved in this way: there are x new books in the school library.

30%×120%x-30%x=30

Solution x=500

A: There are 500 new books in the school library.

There are a total of x copies.

30%x=120%×30%x-30

x=500A: There are a total of 500 new children's books in the school library.

It's not good to copy the answers

If you encounter something you don't understand in the process of doing it, bring it up and everyone can help you.

What I want to tell you is that the answer will not be published on the Internet, I have seen a lot of answers, and I have never succeeded in knowing, and the Ministry of Education must have also issued relevant regulations to do it yourself, overcome inertia, there will never be an answer, if there is, isn't it unfair to your classmates, no, it's not fair to you, you have done less, send you a word - I wish you smooth sailing on the road to study, I hope mine can help you, do it seriously.

2 parts a + 3 ab-2b

-2((1/a)-(1/b))+3]/[-(1/a)-(1/b))-2]=(-2+3)/(-1-2)=-1/3

1/1 + 1/b = 5/a + 5/b

a+b)/a]+[a+b)/b]=5[1+(b/a)]+a/b)+1]=5(a/b)+(b/a)=5-2=3

1 is divided by 1 a-1 b=1 pass to obtain b-a=ab then (2a+3ab-2b) (a-2ab-b)=ab -3ab

2 by 1 a+1 b=5 (a+b).

The left side of the pass is obtained (a+b) ab=5 (a+b) to continue simplifying.

a^2+b^2+2ab)/ab=5

a^2+b^2)/ab=3

i.e. a b+b a=3

1 a-1 b=1, (b-a) ab=1, i.e., a-b=-ab-2ab+3ab) -ab-2ab=-1 3(2)1 a+1 b=5 (a+b) a+b ab=5 a+b, cross-multiplication, (a+b) 2=5ab, obtain, a2+b 2=3ab

a/b+b/a=(a^2+b^2)/ab=3ab/ab=3

1) 1/a-1/b=1

b-a=ab

a-2ab-b=-3ab

2a+3ab-2b=value of 2a+3ab-2b of ab-ab-b - 1 3

2) 1/a+1/b =5/(a+b)(a+b)^2=5ab

a^2+b^2)/ab=3

The value of a out of b + b of a = (a 2 + b 2) ab = 3

1.When Dongdong first caught up with Jingjing, it took exactly one more lap than Jingjing: 200 (6-4) = 100 seconds.

Dongdong ran: 100 6 200 = 3 laps.

Jingjing ran: 3-1=2 laps.

2.Draw a line diagram and take a look.

The age difference between the master and the apprentice remains the same: (37-10) 3 = 9 years old this year, and the master : 37-9 = 28 years old.

Apprentice: 28-9 = 19 years old.

3.Is the order of the words correct?

I don't know if there's the answer you're looking for.

200 (6-4) = 100 seconds.

Dongdong ran 3 laps and Jingjing ran 2 laps.

This year, the master is 28 years old and the apprentice is 19 years old.

Question 1 3, 2

Question 2 28, 19

I didn't understand the third question.。。。

Laps, 2 laps.

2. This year, the master is 28 years old and the apprentice is 19 years old.

I didn't understand the third question either!

÷4n =【2mn+2nm-2nn】/4n=（2m-n）/2

2m - 4+2m)] 2

x(x+1) -3(x²-x)+3x(x-2)=x(x+1) -3x(x-1)+3x(x-2)=x(x+1)+ 3x( x-2 -x+1)=x(x+1)-3x

x(x+1-3)

x(x-2)

Questions 1 and 2 don't show the priority of your question. Follow the answer as I understand it:

2x /（x²-64y²） 1/(x-8y)=2x/[(x-8y)(x+8y)] 1/(x-8y)=[2x - x+8y) ]x+8y)(x-8y)]=(x-8y)/ x+8y)(x-8y)]=1/(x+8y)

1 - x-1）/ x+1) =3/ (x-2)2/(x+1)= 3/(x-2)

3(x+1) =2(x-2)

x = 7

1.(x-8y) (x+8y) 2x - x-8y).

General fraction, (x-8y)(x+8y) 2x-x-8y=(x-8y)(x+8y)x-8y=x+1y/1=[1+(-1 4)*8]1=-1

It's easy to do, it's too annoying to type, so I'm so self-conscious.