![](data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" viewBox="0 0 72 71" width="72"></svg>)
An applied problem in Mathematics "The stationery counter of Fuxing shopping mall bought a batch of" hero "brand pens at the price of a (a is an integer) yuan, and decided to increase the price by 2 yuan for each pen. Because of the excellent price, good quality and beautiful appearance of these pens, they soon sold out. When checking out, the salesperson found that the total sales amount of these pens was (399a + 805) yuan, Based on the above information, can you find out the total number of pens purchased at the stationery counter and the purchase price of each pen? How much is a
Let's say it's X
X（a+2）=399a+805
X=（399a+805）/（a+2）=399（a+2）/（a+2）+7/（a+2）=399+7/（a+2）
Because x is an integer, 7 / (a + 2) is an integer, so a = 5, x = 400
You master, a few mathematical problems, please
(1 / 4-1 / 6) by 12 34 by (2 + 13 / 34) 1 and 3 / 4 by 2 and 4 / 15 by 4 / 7 (11 / 12 + 7 / 18 + 5 / 24) by 72
4.25-three and 5 / 6 - (two and 1 / 6-one and 3 / 4) seventeen and 5 / 6-three and 3 / 4-Four and 5 / 6 125 times 8.8
12:2 / 5 - (1:2 / 7 + 2:2 / 5) 7 / 9 divided by 2:1 / 5 + 5 / 11 multiplied by 2 / 9, 4:1 / 3 + 3.2 + 5:2 / 3 + 6.8
(1 / 4-1 / 6) × 12 = 1 / 4 × 12-1 / 6 × 12 = 3-2 = 134 × (2 + 13 / 34) = 68 + 13 = 811 and 3 / 4 × 2 and 4 / 15 × 4 / 7 = 7 / 4 × 4 / 7 × 2 and 4 / 15 = 2 and 4 / 15 (11 / 12 + 7 / 18 + 5 / 24) times 72 = 11 × 6 + 7 × 4 + 5 × 3 = 66 + 28 + 15 = 1094.25-3 and 5 / 6 - (2 and 1 / 6-1 and 3 / 4) = 4 and 1 / 4-3 and 5
Application of percentages in grade five
There are 1200 students in Guangming primary school, including 576 boys. What percentage of the total number are boys? 2. The price of a semiconductor radio is 165 yuan, which is 85 yuan lower than that of last year. 3. There are 1280 workers in a factory, including 620 female workers
RELATED INFORMATIONS
- 1. If the height of a cuboid is increased by 2cm, it will become a cube. At this time, the surface area is increased by 64cm. What is the volume of the original cuboid 2. Dig out a small piece from a cuboid wood block with a volume of 30cm. What is its surface area; 3. How much is the surface area reduced by kneading a 8cm long, 4cm wide and 2cm high dough into a cube?
- 2. Judgment: After 75% of 1.1 meter cloth is used, 25% of the cloth is left choice: 1. Add 5g sugar and 100g water to the water containing 5% sugar, and the sugar content of the water is () A. Constant B. above 5% C. below 5% Fill in the blanks: 1. A cuboid shaped wood strip can be sawn into seven cube blocks, and the sum of the surface area of all cube blocks is increased by ()%
- 3. According to the state regulations, the tax calculation method for individual publishing articles and books is as follows: 1. No tax shall be paid if the contribution fee is not higher than 800 yuan; 2. 14% of the contribution fee exceeding 800 yuan shall be paid if the contribution fee is higher than 800 yuan but not higher than 4000 yuan; 3. 11% of the whole contribution fee shall be paid if the contribution fee is higher than 4000 yuan; if someone has paid 420 yuan of tax in a lump sum, the tax shall be paid, How much is this person's contribution fee? If paid 770 yuan tax? It's a linear equation with one variable
- 4. It is known that the side length of the equilateral triangle ABC is 4, and point D is a moving point (not coincident with points B and C) on the side BC. It connects AD and makes the vertical bisector of AD and intersects with the sides AB and AC at points E and f respectively, Find the sum of the perimeter of triangle BDE and triangle DCF; Let the length of BD be x, and use the algebraic expression of X to express the perimeter of BDE and CDF;
- 5. The distance between a and B is 400 kilometers. A car drives from a to B for 300 kilometers in 4 hours. At this speed, how many hours will it take to finish the journey
- 6. I'll be on the first day of junior high school next term. I'm not good at math,
- 7. 1: 1.25 × (- 81 / 20) × (- 8) 2: (- 9) × (- 5 / 4) × (- 0.8) × 1 / 3 3: (- 3 / 4) × (- 8 + 10 / 3-1 / 2) 4: 3 / 4 × (- 9) + 3 / 4 × (- 15)
- 8. If we know that the trilateral length of △ ABC is a = 3, B = 5, C = 67, then the area of △ ABC is That's wrong. C = 7
- 9. x/5 + 2x/3 = 39
- 10. The sixth grade donated 460 yuan, 14 yuan less than three times of the third grade. How much for the third grade
- 11. 1. A township originally planned to afforest 12 hectares last year, but actually afforested 14 hectares. How many percent more than the original plan? 2. During the "Eleventh Five Year Plan" period, the Xiaojun family planned to spend 2000 yuan, and the actual consumption was 1800 yuan. How much less was the actual consumption than the planned consumption? 3. Guangming Village has 121 units per 100 households this year, an increase of 66 units compared with last year. How much has this year increased compared with last year? 4. Xiao Ming's mother's monthly salary is 2000 yuan. In the past, her monthly salary was 1800 yuan. Now, how much higher than the original salary? 5. On the morning of October 1, 2009, 240 people in Grade 5 watched the 60th anniversary of the National Day parade on TV, and 300 people in Grade 6 watched the 60th anniversary of the National Day parade?
- 12. There are three numbers a, B and C. the number a is 70 times more than the number B, and the number B is 10 times more than the number C. The sum of three numbers is 244 The total number of students in school a, B and C is 2640, of which the number of students in school a is three times that of School B, and the number of students in school B is 2.5 times that of school C. how many students are there in each of the three schools? Six times of a number, minus the difference of 26, and 26 plus the sum of a number equal to find a number Wang Bodong collected a total of 2750 kg of rice and corn last year, which is 250 kg more than three times that of corn. How many kg are rice and corn?
- 13. A cone-shaped sand pile has a bottom circumference of 31.4 meters. A car can transport 8 cubic meters at a time. How many times can it be transported? (keep the number in integer)
- 14. A shopping mall participated in the financial insurance, the amount of insurance is 40 million yuan, the insurance rate is 0.75%. An accident, the loss of goods worth 6.5 million yuan, the insurance company compensate 5 million yuan. How many million yuan is the actual loss of the shopping mall?
- 15. 1. Given the cost function TC = 30000 + 15q-3q (the square of Q) + Q (the third power of Q), q is the output quantity. 1) when the output is 500 units, what is the TFC? 2) when the output is 30, what is the AVC? 2. Known investment function I = 300-100r, savings function s = - 200 + 0.2y, money demand function L = 0.4y-50r, total supply M = 250, total price level P = 1. Find is and LM Curve equation
- 16. 1. A project! Team a will do it alone, and it will be completed within the specified date! If team B will do it alone, it will take more than 3 days. Now team B will do it alone two days later, and it will be completed within the specified date! Question: what is the specified date? 2. Make a new coating with 100 yuan a coating and 240 yuan B coating! The total value remains unchanged! The new coating is sold 3 yuan less per kilogram than a coating and 1 yuan more than B coating per kilogram! What's the price of this new coating? Drought is coming! A middle school donated 1800 yuan to class a of Grade 8, and 1560 yuan to class B. It is known that class A is 1.2 times the average donation of class B, and class B has 2 more people than Class A. how many people are there in each class?
- 17. The deduction standard of junior high school mathematics fraction application questions The number given in the original question is 1.25. How many points can I give to my whole fractional equation according to the 1.5 column?
- 18. 1. The translation efficiency of an electronic receiver is 75 times of that of human. How many times of that of an electronic receiver? 2. For a project, if Party A works alone, it will be completed as scheduled, while if Party B works alone, it will be delayed for 3 days. Now, Party A and Party B cooperate for 2 days, and the rest will be done alone by Party B, which will be completed as scheduled?
- 19. Primary school mathematics problem-solving steps and methods, to be detailed!
- 20. Love primary school bought 12 desks and 16 chairs to donate to teachers in Yingjiang, Yunnan Province. The total cost of desks and chairs was 3150 yuan. Each chair is 70 yuan cheaper than each desk. How much is each desk and chair?