A math problem that we re going to solve in the third grade

From "Dad's salary is twice that of Mom's salary", it can be seen that the salary of Dad and Mom is 3 times in total;

360 yuan" "is exactly 1 and a half of the total salary of mom and dad".

Then the sum of the salary of mom and dad is: 360 2 720 (yuan) The salary of dad and mom is 3 times in total, and 1 time (mom's salary) is:

720 3 240 (yuan).

Dad's monthly salary is: 240 2 480 (yuan).

According to the meaning of the title, the sum of the salary of mom and dad is 360 * 2 = 720 yuan, let the mom's salary be x yuan, then the dad's salary is 2x yuan, list the equation 2x+x=720, and solve x=240, 2x=480, so the father's monthly salary is 480 yuan.

Dad's salary is 480 yuan.

Dad's salary is twice that of Mom, and 360 is half of the sum of the two of them, so 360 accounts for 2 3 of Mom's salary, then Dad's salary is 360*2 3*2

If Lingling's mother's salary is x, then Lingling's father's salary is 2x2x-360=x+2x 2

6x-720=3x

3x=720

x=240, so Lingling's father's salary is 2x=480 yuan.

x/y=2x-360=(x+y)/2

Open the equation. You're an elementary school student.

Is there a 2-element equation?

For a third-grade child, it is best to use a picture to help him understand.

Red accounts for the total length of the :

Yellow accounts for the total length of the :

1. Red accounts for the total length:

Both ends are painted red, so the total amount of red is: 3 8 + 3 8 6 8, about 3 4

Second, yellow accounts for the total length:

Subtract the red total length with the overall 1: 1-3 4 1 4

Generally, the painted parts at both ends of the toy stick should be the same length, so the red is 3 8 2 = 3 4

The rest is yellow, so, 1-3 4 = 1 4

Red accounts for the total length: (3 8)x2 = 3 4, yellow accounts for the total length: 1-3 4 = 1 4.

It is known that the speed of the younger brother is 1 meter per second, so the distance between Xiaohong and the younger brother when he first comes out is 20 meters.

Set the time to x seconds, then the distance that Xiaohong has traveled is 2x meters, and the distance that the younger brother has traveled is x meters, then the distance between Xiaohong and the younger brother can be expressed as: 20-2x+x=20-x meters, when Xiaohong catches up with the younger brother, that is, the distance between the two is 0, that is, 20-x=0, x=20 seconds, and the speed of the puppy is 5 meters per second, then the puppy needs to run 5*20=100 meters. ^_

First of all, 20 seconds, my brother walked 20 meters, so how long does it take for my sister to catch up with my brother, is 20 meters divided by how fast my sister is faster than my brother.

The elder sister walks 1 meter per second faster than the younger brother, so it takes 20 divided by 1 = 20 seconds, 20 seconds, and the dog's speed is 5 meters per second, so the core of running 20 * 5 = 100 meters is that the dog is running, and how long does it take for the elder sister to catch up with the younger brother.

First find out the time it takes for Xiaohong to catch up with her brother, 2x=20*1+x

Find x = 20 seconds.

Before Xiaohong catches up with her younger brother, the distance that the dog has to run is 20 * 5 + 20 * 2 = 140 meters When Xiaohong came out, the distance that the puppy ran was the same as that of the younger brother, and the puppy had been running before Xiaohong caught up with her brother.

Let's leave the dog alone anyway, he's running non-stop, let's calculate the time it takes for Xiaohong to catch up with his brother first.

Set the time to x2x=20+x

x=20;

Then the distance that the dog runs is s=20*5=100 meters.

If the older sister sets off in 20 seconds, and the younger brother is traveling at 1 meter per second, and the older sister is traveling at 2 meters per second, then the older sister still needs 20 seconds to catch up with the younger brother, and the dog is traveling at 5 meters per second.

So the dog has to run a distance of 100 meters.

The distance between the elder sister and the younger brother.

The distance from home to school is meters, and the distance from company to school is meters, so my mother walked a total of meters.

From front to back, it is Xiaoli, Xiaoqiang, Xiaohua, and Xiaoxin.

The first is small force, and the difference between small force and small new is one meter.

This question mainly exercises such a type of question:

One. How many numbers are there from 1-9? What about 0-9? Answers: 9, 10.

Two. How many days are the dates from 1st to 9th? 9 days.

Three. Trees are planted on the nine-meter straight road, one per meter, and a total of 10 trees are planted.

Four. Trees are planted on the nine-meter ring road, one per meter, a total of 9 trees are planted.

Five. The first to the ninth floor of the stairs has to be climbed on a total of eight floors.

As long as you figure out the above situations, there will generally be no confusion.

This kind of question is closely related to real life, and the above controversy arises, I think the main reason is that the teacher did not understand the essentials of exercise.

It should be counted as nine days, and the person who wrote the question only considers the subtraction of elementary school students: 18-10=8. But the real situation is not taken into account at all.

Seriously out of touch with reality. If there is also a tour on the 18th, the time of the tour should include the 18th, but in the subtraction operation, the 18th day is subtracted. If you want to ask elementary school students to calculate addition and subtraction, you can use similar problems such as eating apples.

When calculating the number of days, you can't add or subtract them in this way.

It's 9 days to go out, but if you come back on the 18th, it should be 8 days of travel, and you want to go from the 10th, count it as a day, but come back on the 18th and it's not a tour.

This kind of question is the least interesting. It's not good at all.

It's nothing more than wanting to assess whether you know the concept of plus 1, as long as you really understand it, you don't have to care too much about right or wrong.

I don't think there's a right answer, the constraints of the question aren't clear enough, and either 8 or 9 has its own reasons, and the key is when the tourist arrives on July 10th.

It's not clear what I'm asking, and it's not clear what I'm asking....That is, from leaving to going home, counting is 9 days...But it is not clear whether it counts as the day of departure and the day of return.

The day is 24 hours.

If you leave on the 10th and come back on the 11th, it will be 1 day.

It was 8 days since I left on the 10th and came back on the 18th.

Look at the 18th day of the travel no, if you swim, it is 9 days, or there is 8 days, this question is controversial, the topic itself is not rigorous.

I feel like it's 8 days, because July 10th to July 18th is 8 days, but if you go out on this day and it's a tour, it's 9 days, the thinking is different, and the answer is different! I hope it helps.

It depends on whether you come back in the morning or evening on July 18th.

But there's no need to dwell on this issue.

There will be no such questions in the official exam questions in the future.

Keep it simple·· July 10 - July 18 = 8 days of play. The best way to do this is to ask these teachers what they think about this question.

If you leave on the 10th and come back on the 11th, it will be 1 day. (Daytime on the 10th.) Daytime on the 11th).

It was 8 days since I left on the 10th and came back on the 18th.

I think it's 8 days, the day I went is counted, it's a day, and I came back on the 18th, so it shouldn't be counted.

It should be 8 days.

9 days, unless he sleeps on July 10th.

The teacher made a mistake.

Trust me.

I also hit the nail in the problem at school last year. Go and ask the teacher, when did you go? When did you come back?

If you go on the morning of the 10th and return late on the 18th, it will take 9 days; If you go on the morning of the 10th and return on the morning of the 18th, or go late on the 10th and return late on the 18th, it will take 8 days.

Be sure to ask the teacher!! It's hard for them!!

I went out on the 10th, I was a tourist on the 10th, I came back on the 18th, I couldn't be a tourist on the 18th, and I was already at home on the 18th.

The teacher is right, because I went out on July 10th, and I counted all the numbers out, and I came out 10 11 12 13 14 15 16 17, and I was traveling because I came back on July 18th, so I wasn't traveling.

So it is 8 days for the watchtower lord to adopt.

18-10+1=9 days.

I think it's 9 days, that's how the elementary school teacher taught, and I've just graduated now.

It should be 9 days, because the day of going out and coming back is the tourist time.

Number 10. Number 11. Number 12. Number 13. Number 14. Number 15. Number 16. Number 17. Number 18. A total of nine days.