There are two kinds of pens, a and B. their price ratio is 2:1. If the price is reduced by 5 yuan, their price ratio is 9:2. What are the original prices of these two kinds of pens?

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• 1. We only need to use fraction four mixed operations A bookshelf has two layers, the upper and the lower, with a total of 128 books. The ratio of the number of books on the upper and the lower layers is 5:3. How many more books are there on the upper layer than on the lower layer? (mixed operation with four fractions.) Here's how it works 5+3=8 Upper layer: 128 / 8 * 5 = 80 (this) Lower layer: 128 / 8 * 3 = 48 (this) 80-48 = 32
• 2. Pave a 2-meter-wide path around a 37.68-meter-long circular pool. How many square meters is the area of the path?
• 3. There are three digital cards of 0.35, which make up a three digit number. What is the percentage of 0 at the end?
• 4. One fifth of the students in class 6 (1) participated in the cleaning, and then two students took the initiative to participate in the cleaning One fifth of the original students in class 6 (1) participated in the cleaning, and then two students took the initiative to participate. The actual number of participants was one-third of the number who did not. How many students participated in the cleaning?
• 5. The sixth grade Mathematical Olympiad questions and answers 100
• 6. Primary school sixth grade mathematics problem 100, urgent
• 7. Young pioneers participated in the exhibition of environmental protection. 120 people went to the exhibition on the first day, 30 less than 1.5 times the number on the second day. How many people went to the exhibition on the second day?
• 8. In sunny days, it takes 12 days for team a to complete the task, and 15 days for team B to complete the task. In rainy days, the work efficiency of team a will decrease by 50%, and that of team B will decrease by 25%. In the last two construction teams to start and complete the two projects at the same time, there will be more difficulties in rainy days_____ Day two One by one, one answer, two answers, two answers, three answers,
• 9. Practical questions: ① A rectangular reed mat with a length of 9.42 meters and a width of 6.28 meters is enclosed to form a grain storage bin. There are several different enclosure methods? What's the maximum volume? (the joint is not included) (the number obtained remains the whole cubic meter) ② A cone-shaped sand beach is 12.56 meters long and 9 meters high. How long can it be paved on a 5-meter-wide road with 2 cm thick sand? ③ A cylinder has a base area of 62.8 square centimeters and a height of 8 centimeters. A cone has the same volume and base area as it. What is the height of the cone? Fill in the blanks: ① A cylinder and a cone are of equal height and equal bottom. The sum of their volumes is 64 cubic decimeters, and the volume of a cone is () cubic decimeters? Judgment questions: ① The volume of a cone and a cylinder are equal, the area of the bottom is equal, and the cone is two-thirds higher than the cylinder
• 10. 1. The number of defective machine tools is one ninth of the number of genuine machine tools. After review, it was found that one of the genuine machine tools is unqualified. At this time, the number of defective machine tools is three-thirds of the number of genuine machine tools. How many machine tools are there in total? 2. A box of sugar weighs 500g. If you eat two fifths of this box of sugar and the rest weighs 340g, how much does the original sugar weigh? 3. A shopping mall delivered a batch of soap and sold 15 boxes less than one sixth of the soap. At this time, 87.5% of the soap was not sold. How many boxes are there in total? 4. There are 52 workers in a workshop, one fourth of them are male workers, one less than one third of them are female workers. How many are male and female workers in this workshop? 5. The speed of the local train is 5 / 7 of that of the express train. The two trains leave from station a and station B at the same time and go in opposite directions. They meet 36 kilometers away from the midpoint. How many kilometers did the express train travel when they meet? Try not to use equations to solve these five problems, Equations are OK. Send the answers
• 11. Mr. Zhang's salary in December last year was 3000 yuan. After deducting 2000 yuan, he paid personal income tax according to the standard on the right. Mr. Zhang should pay personal income tax in December______ Yuan
• 12. In 2012, the number of days with excellent air quality in our city accounted for 3% of the whole year. How many days with excellent air quality in 2012 Two minutes to answer
• 13. I don't know how many days there are in the first half of a leap year?
• 14. P is the point on the right branch of hyperbola x29-y216 = 1, m and N are the points on the circle (x + 5) 2 + y2 = 4 and (X-5) 2 + y2 = 1 respectively, then the maximum value of | PM | - | PN | is () A. 6B. 7C. 8D. 9
• 15. Circle (x-1) ^ 2 + (Y-1) ^ 2 = 9, through a (2,3) as any chord of the circle, find the trajectory equation of the midpoint P of these chords No pictures,
• 16. As shown in the figure, in the plane rectangular coordinate system, the endpoint coordinates of line AB are a (- 2,4), B (4,2), and the line y = kx-2 has an intersection with line AB, then the value of K cannot be () A. -5B. -2C. 3D. 5
• 17. How to draw the image of parameter equation x = 1-T ^ 2, y = t - ^ 3?
• 18. It is known that the equation of a circle is (x-1) 2 + y2 = 4. A point a (4,2) (1) outside the circle solves the tangent equation of the circle passing through point a
• 19. If there is a common point between the line L passing through point a (4,0) and the curve (X-2) 2 + y2 = 1, the range of the slope of the line L is () A. [−3，3]B. (−3，3)C. [−33，33]D. (−33，33)
• 20. In the triangle ABC, the opposite sides of angles a, B and C are a, B and C respectively. We know that a = 2, C = 3 and CoSb = 1 / 4