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Xiaoming Xiaobai goes to buy books. Xiaobai borrows money to buy Xiaoming a dictionary. He has 20 yuan left. Xiaoming borrows money to buy Xiaobai famous books I have 4 yuan left. The price of the famous book is three times that of the dictionary. How much are the two books? No XY. Please use the formula (such as (59 + 3) / 5) and the equation Two kinds of formulas (the price of dictionary and the price of famous works)
The two of them have 20 yuan left for the dictionary,
There are four yuan left for the famous works
in other words
Famous works cost 20 yuan - 4 yuan = 16 yuan more than dictionaries
The price of famous works is three times that of dictionaries
The price of a famous book is twice that of a dictionary
The price of the dictionary is (20-4) / 2 = 8 yuan
The price of famous works is: 8 * 3 = 24 yuan
Does Xiao Hong do ten math problems? Is there a positive proportion between the problems she has finished and the problems she hasn't done? Explain the reason
Xiao Ming does ten math problems. The problems he has done and the problems he hasn't done can't make up a proportion
Because the problem that has been done + the problem that has not been done = the total problem that needs to be done (certain), because it is and certain, not a certain ratio, so it cannot form a proportion
Please explain in words)
1. Among the three classes, class a accounts for 1 / 3 of the total, 10 people less than class B. the ratio of class A and class B to class C is 5:2. How many people are in class C?
2. In the first half of the semester, boys accounted for 5 / 6 of the number of girls. After three more boys came on holiday, boys accounted for 6 / 7 of the number of girls. How many students are there in this semester?
1. Among the three classes, class a accounts for 1 / 3 of the total, 10 people less than class B. the ratio of class A and class B to class C is 5:2. How many people are in class C?
5 / (5 + 2) = 5 / 7
C: 2 / [5 + 2] = 2 / 7 of the total
Class B: 5 / 7-1 / 3 = 8 / 21
So the total number is: 10 / [8 / 21-1 / 3] = 210
Class C: 210 * 2 / 7 = 60
2. In the first half of the semester, boys accounted for 5 / 6 of the number of girls. After three more boys came on holiday, boys accounted for 6 / 7 of the number of girls. How many students are there in this semester?
The number of female students is: 3 / [6 / 7-5 / 6] = 126
Now there are: 126 * 6 / 7 = 108 boys
Total: 108 + 126 = 234
The number of male workers in a factory is 35% of that of female workers, and the number of female workers accounts for 35% of the total number of workers in the factory______ %
5: (8 + 5) = 58 = 0.625 = 62.5%; so the answer is: 62.5%
When x = half and y = one third, find the value of X - (x + y) + (x + 2Y) - (x + 3Y) +. - (x + 101y)
x-(x+y)+(x+2y)-(x+3y)+.-(x+101y)
=X-x-y + X + 2y-x-3y +. - x-101y
=-Y + 2y-3y + 4Y -... + 100y-101y, we find that all x can be reduced and only y is left
=(- y + 2Y) + (- 3Y + 4Y) +... + (- 99y + 100y) - 101y, every two items are combined, and they are equal to y in brackets
=There are 50 Y's in 50y-101y
=-51y
=-55 / 3 of the results are negative~
At the London Olympics, the Chinese sports delegation won 27 silver medals. The gold medal is about 40.7% more than the silver medal, and the silver medal is about 17.4% more than the bronze medal
How many gold medals and how many bronze medals did you win?
∵ gold medal is about 40.7% more than silver medal
The number of gold medals = the number of silver medals × (1 + 40.7%) = 27 × 1.407 = 38
∵ silver is about 17.4% more than bronze
Number of bronze medals = number of silver medals / (1 + 17.4%) = 27 / 1.174 = 23
He won 38 gold medals and 23 bronze medals
Given that X and Y belong to the interval (- 2,2), xy = - 1, find the minimum value of u = 4 / (4-x2) + 9 / (9-y2)
Another problem is: given the equation x2 + (1 + a) x + 1 + A + B = 0, two of them are x1, X2, if 0
Here's an idea
1. Let x = 2sinx = [- 2,2]
y=3siny=[-2,2]
The product = - 1 and the value range is known
It is easy to find u = sec ^ 2x + sec ^ 2Y
2. The parabolic opening is upward and 0
The number of female students in the school sports team is 23% of that of male students?
(1-23) △ 23, = 13 × 32, = 12, = 50%; a: boys are 50% more than girls
An integer has two square roots, right
Write why
8 pairs
Square root number:
In real number range
Positive 2
0 1
Negative 0
In the plural
Positive 4 2 real 2 conjugate complex number
0 1
Negative 2 conjugate complex number
The average number of a, B and C is 120. The ratio of a, B and C is 1:2:3. What are the three numbers
Sum = 120 × 3 = 360
360÷(1+2+3)=60
A = 60 × 1 = 60
B = 60 × 2 = 120
C = 60 × 3 = 180
RELATED INFORMATIONS
- 1. There are 10 required answers, and 20 points will be deducted for one wrong answer. Xiao Ming got 40 points. How many wrong questions did Xiao Ming get? How many questions can be answered correctly? Can right and wrong be restored? Xiao Ming gets 40 points, and how many questions can Xiao Ming answer correctly? Xiao Ming should get 80 points if he answers 8 questions correctly, but Xiao Ming gets 40 points
- 2. Xiao Ming, Xiao Hong and Xiao Fang did 72 math problems. Xiao Ming did 8 more than Xiao Hong, and Xiao Fang did 12 less than Xiao Ming and Xiao Hong What's wrong with each other?
- 3. Every page of Xiaoming's diary is numbered with 981 numbers from 0 to 9. Please figure out how many pages there are in Xiaoming's diary! Every page of Xiaoming's diary is numbered. He uses 981 numbers from 0 to 9. How many pages does Xiaoming's diary have? There should be a process and answer questions
- 4. There are 15 questions in total, 8 points for one right question, 4 points for one wrong question and 72 points for Xiao Ming. How many questions have you answered correctly? You can't use negative numbers or X to express, the simpler the better
- 5. The mathematics interest group held a test. There were 15 questions in the whole paper. It was stipulated that 8 points would be deducted for each right question and 4 points would be deducted for each wrong question. Xiaoying got 72 points in total, and she did it right______ Question
- 6. Baidu asked Xiaoming to do math problems, each right one plus 10 points, do a wrong deduction of 5 points, a total of 10 questions, the final 55 points ask right and wrong each several questions extra urgent
- 7. Master Wang made a light box with 78.5 square centimeters of openings in the middle of the top and bottom. How much colored paper did he use? 20cm in diameter
- 8. The circumference of a cuboid is 80cm, and the ratio of length to width is 4:1. What's the area of the cuboid? Tao Jie and Jiang Tao travel from a to B at the same time, and their speed ratio is 4:3. Tao Jie travels 20 kilometers per hour, and Jiang Tao travels how many kilometers per hour?
- 9. Help me solve a math problem and answer it in a minute! When Li Mengmeng read a book, he read one third of the whole book on the first day, and 18 pages more than 25% of the whole book on the second day. At this time, the ratio of the number of pages read to the number of pages not read is 3:1. (1) how many pages are there in the book? (we can't use equations to solve it, we must use equations) (2) how many pages did he read the next day?
- 10. When Xiao Ming reads a book, the number of pages he has read is 32 of the number of unread pages. When he reads another 30 pages, the number of pages he has read is 73 of the number of unread pages. How many pages are there in this book?
- 11. Xiaoming and I want to buy a toy car for 28 yuan, so each person should pay 14 yuan, but I have no money, so I borrow 14 yuan from Xiaohua (Xiaohua also wants it, so he agrees to buy a toy car with me for 7 yuan, but Xiaohua gives it all). How much money should I pay back to Xiaohua?
- 12. Three students are taller. As a result, Xiaojun is 1 / 12 meters shorter than Xiaoming and 1 / 20 meters higher than Xiaofang. How many meters is the tallest one higher than the shortest one
- 13. Xiaoming is 142 cm tall, a cm shorter than Xiaohua, and Xiaohua is () cm tall
- 14. Xiaoming's height is 112 cm higher than Xiaojun's, and Xiaojun's height is 12 cm shorter than Xiaoming's______ ．
- 15. Xiao Gang is 140 cm tall. Xiao Gang is 27 times higher than Xiao Ming. How many cm is Xiao Ming?
- 16. Xiaogang and Xiaoqiang practice running on the 400 meter circular track. Their speed is 200 meters per minute and 160 meters per minute respectively
- 17. Xiao Gang used to have some pictures. He took out half of them and gave them to his younger brother. Later he bought 18 more. At this time, there were 47 pictures. How many pictures did he have?
- 18. Xiaoming starts from a at 8 a.m. and goes to B at 20 kilometers per hour. 15 minutes later, Xiaogang starts from a and goes to B at 6 kilometers per hour In B, Xiao Ming takes a 60 minute rest in B and then returns to A. on the way back, he meets Xiao Gang who starts from A. at this time, they are 2 kilometers away from B. find the distance between a and B
- 19. Xiaoming starts from a at 8 a.m. and goes to B at 20 kilometers per hour. 15 minutes later, Xiaogang starts from a and goes to B at 16 kilometers per hour In B, Xiao Ming takes a 60 minute rest in B and then returns to A. on the way back, he meets Xiao Gang from A. at this time, they are 2 kilometers away from B. find the distance between a and B
- 20. Xiaohong and Xiaoqiang start from home at the same time. Xiaohong walks 52 meters per minute and Xiaoqiang 70 meters per minute. They meet at a on the way. If Xiaohong starts 4 minutes ahead of schedule and Xiaoqiang walks 90 meters per minute, they still meet at a. how many meters are Xiaohong and Xiaoqiang's homes apart?