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From the problem: numerator (denominator + 2) = 7 9

Numerator (denominator +3) = 3 4

Only the denominator has changed, and the numerator has not changed, so it is enough to unify the numerators of the above two formulas into the same number.

Numerator (denominator +2) = 7 9 = 21 27

Numerator (denominator +3) = 3 4 = 21 28

Denominator +2 = 27

Denominator +3 = 28

This gives us the denominator = 25

So the score is: 21 25

Since there is no change in the molecule, the least common multiple of the molecule is found.

i.e. the least common multiple of is 21

Multiply the denominator by 28

Since 21 27 denominator is added 28 denominator is added 3

So the -3 score is 21 25

The molecule does not change, and the molecule becomes the same.

7/9 21/27

3/4 21/28

It turns out that this score is.

28 3) 21/25

Find the least common multiple of the numerator: 21

Converting two fractions into fractions with a numerator of 21 gives 21 27 and 21 28

According to the title, the original denominator is 25, so the original fraction is: 21 25

I tried it one by one, and it was 21/25

Summary. Classmate: Send me your question.

Classmate: Send me your question.

I'll just ask you a little question.

It is known that m 0, the absolute value of negative root number 2 plus m = root number 2 plus m, right. Student: That's right.

It is known that the left and right focal points of the ellipse c: A+y2=1 are f, f2 respectively, and the straight line y=x+m and c intersect at a, b two points, if the area is 2 times the area of a f2ab, then m=() If the absolute value of the root number 2 plus m is equal to the root number 2 plus m, there is no answer to the calculation, and the m can only be regarded as a number greater than 0, so that the absolute value of the thick and negative root number 2 plus m will be equal to the root number 2 minus m.

a stands for triangle.

The fifth question is C.

Question 6 is also C

The answer to question 7 is d

The answer to question 8 is -85

If you haven't learned equations.

The premise is as empty as a pool.

A pool of water can be filled with water for 6 hours.

That is, the water inlet for one hour is 1 6

A pool of water can be completed in 9 hours by opening the water pipe alone.

That is, the opening of the water for one hour on a business trip is 1 9

i.e. one hour. At the same time, the water is opened in and out.

Can be water inlet 1 6-1 9 = 1 18

So the answer is 1 2

Divide by 1 18

Wait early in the absence of 1 9

The premise is that the pool is empty.

A pool of water can be filled for 6 hours by driving the water inlet alone.

That is, the incoming jujube shouts for 1 6 an hour

A pool of water can be completed in 9 hours by opening the water pipe alone.

That is, the water is 1 9 for one hour

Suppose it took x hours to put a bench stove in the field and half a pool.

then (1 6-1 9)x=1 2x=9

The Math Tutoring Team is definitely a strong and helpful team. There are mathematical talents, mathematical talents, and mathematical overlords from all over the country! I believe that you can solve your difficult problems more, quickly, well, save land and completely! So, feel free to ask your questions!

The nature of the problem is the same, the first question, set the person who produces the chair for X people, and the person who produces the table for Person Y. Then there is x+y=480,5x=7y,solve the system of equations,x=280,y=200、The second question is the same, set the production frame for a person, the production of the rim for b people, there is a + b = 408, 15a = 42b, but it seems that the integer can not be solved, I did not calculate carefully, you see if the number is correct.

Finally, take a good class, children, use your own brain to think, and you will learn math well.

1. Solution: If x people are assigned to produce desks, then (480-x) people produce chairs.

5x=(480-x)x7 Since a table is equipped with a chair, the number of tables produced per day should be equal to the number of chairs produced per day.

Solution: x=280 people, then there are 200 people who produce chairs2, solution: assuming that x people are assigned to produce frames, then there are (408-x) people to produce rims.

2x15x=(408-x)x21 Because one frame has two rims, the frames produced per day should be twice as many laps per day.

Solution: x=168 people then there are 240 people who produce chairs.

There are 36 students in the reading room, of whom 4 9 are girls.

So 36*4 9=16 for girls

Set up x more girls.

x+16）/(x+36)=9/19x=2

Solution: There are x girls again.

36+x)×9/19=（36×4/9+x）324/19+9x/19=16+x

x-9x/19=324/19-16

10x/19=20/19

x=2A: There are 2 more girls.

Here are x more girls.

It turns out that there are 36*4 9=16

16+x)/(36+x)=9/19

x=2 more girls.

(25 20%+2 30%+a 50%) to (20%+30%+50%) 64-6).

5+a≥>64

Regardless of Kaodi. The source will not be kicked out of the baiBut du, you'd better work hard to take the test, maybe you take the first place - dao praise!

Yes, you should use a weighted average for each grade and then rank, but if you have a second place, it shouldn't be possible.

...Grades can't be counted like this, they should be counted as scores, not rankings, right?

This question belongs to the problem of unit price and bai, obviously a dujin of bamboo shoots can be sold for 10 yuan, and zhi actually doesn't care about bamboo shoots dao or bamboo shoots, there is no version to reach this **, so it is a loss.

In the case of 50 catties of bamboo shoots and bamboo shoots, the bamboo shoots and bamboo shoots should complement each other, if the bamboo shoots are only sold for 5 Wen, then the bamboo shoots should be sold for 15 Wen, not 5 Wen. In this way: 50 catties of bamboo shoot skin get 50 5 = 250 Wen; 50 catties of bamboo shoots 15 Wen = 750 Wen, a total of 1000 Wen.

Similar question: A man went to buy green onions.

Ask how much is a pound of green onions.

The person who sells green onions says, "1 yuan and 1 catty, this is 100 catties." After 100 yuan, the person who bought green onions asked again, "Do you sell green onions separately?"

The person who sells green onions says that the green onion is white 7 cents and the green onion is 3 cents.

The people who bought the green onions bought it.

Weigh 50 catties of green onion white and 50 catties of green onion.

The last calculation of green onion white 50 * 7 is equal to 35 yuan.

Green 50*3 is equal to 15 yuan.

35+15 equals 50 yuan.

The person who bought the green onion gave 50 yuan to the person who sold the green onion and left.

And the man who sold the green onion wondered.

Why do you want to sell green onions for 100 yuan?

And why did the person who bought the green onion buy it for 50 yuan?

Why do you say that?

This question belongs to the problem of unit price and quantity, obviously a pound of green onions can be sold for 1 yuan, but in fact, regardless of green and white, it has not reached this **, so it is a loss. In the case of 50 catties of white and green, white and green should complement each other, if the green onion is only sold for 3 cents, then the green onion white should be sold for yuan, not 7 cents.