Primary School Mathematics Graduation Exam Question Collection Judgment 50

Let the velocity of A be x, then the velocity of B is 3 5x, and the distance between ab is set to s

Then the time at the time of the encounter is equal to the equation (3 7s+66) x=[s-(3 7s+66)] (3 5x).

It can be seen that the variables x cancel each other out. This yields s = 336 (km).

66÷(5/8-3/7)=336

The speed ratio is 5:3, so the distance ratio of cars A and B is also 5:3. It is also said that when car A and car B met, A traveled the whole 5 8.

Now there are three elementary school math problems, I would like to ask you for any help, thank you in advance.

1.Xiaofei participated in an English competition, with a total of 20 questions, stipulating that she would get 5 points for a correct question, and not only would she not be awarded points for a wrong question, but she would also be deducted 2 points, and she scored 79 points. Do you know how many questions she got wrong?

2.The starting fare of a taxi in Suzhou is 10 yuan for 3 kilometers, and then 1 kilometer per hour to pay yuan, and Yuanyuan and her father pay the fare from home to grandma's house. How many kilometers is there from Yuanyuan's house to my grandmother's house? (Column Equation Solution).

3.There are two piles of chess pieces A and B, the number of pieces in pile A is half of that of pile B, if you take 9 pieces from pile B and put them in pile A, then the number of pieces in the two piles will be the same. How many pieces are there in the original pile?

1.Xiaofei participated in an English competition, with a total of 20 questions, stipulating that she would get 5 points for a correct question, and not only would she not be awarded points for a wrong question, but she would also be deducted 2 points, and she scored 79 points. Do you know how many questions she got wrong?

If you get all the answers right, you deserve:

20 5 = 100 points.

More than it actually is :

100-79 = 21 points.

Doing one wrong question is less than the original:

5+2=7 points.

How many questions did she get wrong:

21 7=3 questions.

2.The starting fare of a taxi in Suzhou is 10 yuan for 3 kilometers, and then 1 kilometer per hour to pay yuan, and Yuanyuan and her father pay the fare from home to grandma's house. How many kilometers is there from Yuanyuan's house to my grandmother's house? (Column Equation Solution).

Solution: It is about x kilometers from Yuanyuan's house to my grandmother's house.

x=53.There are two piles of chess pieces A and B, the number of pieces in pile A is half of that of pile B, if you take 9 pieces from pile B and put them in pile A, then the number of pieces in the two piles will be the same. How many pieces are there in the original pile?

Solution: If A originally has x seeds, then B will have 2x seeds.

2x-9=x+9

2x-x=9+9

x=18

Mom bought Xiaoli a box of calcium tablets, and the instructions read:

Product name: calcium tablets.

Net contents: Grains.

Dosage: 1 to 2 grams twice a day.

According to the instructions, how many days can Xiaoli take this box of calcium tablets?

One gram, then you have to eat 2-4 grains at a time, a total of 100 grains, 100 4 = 25 (days) can be eaten for at least 25 days.

100 2 = 50 (days) can be eaten for up to 50 days.

A: Xiaoli can eat it for 25-50 days.

For a project, A completes it in 5 hours, B completes it in 7 hours, and A and B cooperate for 1 hour.

This is an engineering problem, and this project is regarded as "1", where A completes in 5 hours is 1 7, and B completes in 7 hours is 1 5

The equation is: 1 7 + 1 5 = 12 35

This step can be omitted] Xiaolu