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The school plans to buy 40 pens and some notebooks (the number of notebooks exceeds the number of pens). The price of both a and B plus the stationery shop is 10 yuan for each pen and the number of notebooks It's 2 yuan per book. The preferential way of shop a is 10% off for pens and 20% off for notebooks. Shop B's preferential way is to give one notebook for every five pens. Pens are not discounted, and notebooks are 7.5% off. So how to buy more cost-effective (please see the title and come back) good bonus points
If you buy a notebook and it has a > 40, then it has:
The cost of buying in store a is:
40X10X0.9+2aX0.8
=360+1.6a
The cost of buying in store B is:
40X10+2(a-8)X0.75
=388+1.5a
When a ＞ B, there are:
360 + 1.6A > 388 + 1.5A: a > 280
That is: when the number of laptops purchased exceeds 280, it is cost-effective to buy them in shop B!
When a = B, there are:
360 + 1.6A = 388 + 1.5A, a = 280
That is: when the number of laptops bought is 280, it is the same in a and B stores!
III Dangjia
Supermarket stationery prices are as follows: 8 yuan for each pen, 2 yuan for each pencil, 7.7 yuan for each box of colored pens, 4.5 yuan for each pair of tripods, 1 yuan for each ballpoint pen, 1.8 yuan for each rubber. (1) Xiaohua belt is 10 yuan, you can buy the above stationery at most? (2) How many yuan does Xiaohua have to take to buy the above three stationeries? (3) How much discount are these six kinds of stationery sold? Can Xiaohua take 20 yuan to buy them all?
(1) 2 + 4.5 + 1 + 1.8 = 6.5 + 1 + 1.8 = 7.5 + 1.8 = 9.3 (yuan) 9.3 ＜ 10 answer: you can buy up to 4 kinds of stationery. (2) 2 + 1 + 1.8 = 3 + 1.8 = 4.8 (yuan) answer: at least 4.8 yuan. (3) 20 △ 25 = 80% = 20% discount
I bought a pen, ruler, eraser and stationery and rushed home
I bought a pen, ruler and eraser and hurried home
I bought stationery and rushed home
Given that the derivative of function f (x) is f '(x), how to find the derivative of function [f (x)] ^ 2?
2·f'（x)·f(x)
This is a composite function
Finding the differential of y = x ^ 2E ^ 2x
y=x^2e^(2x)
dy=[ 2xe^(2x) + 2x^2e^(2x) ] dx
u=x^2 v=e^w w=2x
y=uv
dy=vdu+udv
du=2xdx
dv=dw *v
dw=2dx
dy=[2xe^2x + 2x^2e^(2x)]dx
A rectangular vegetable field, with an area of 65 square meters and a width of 5 meters, how long is the vegetable field
We can't understand whether it's perimeter or length
From the meaning of the title, it is to seek the length of vegetable land
65 △ 5 = 13m
A: this vegetable field is 13 meters long
How many centimeters is eight cubic minutes
One is the volume unit and the other is the length unit. It is impossible to convert
8 cubic decimeter = 8000 cubic centimeter
The period of the function y = cos ^ 2 (x) is?
Such as the title
cos2x=2cos²x-1
So y = (1 + cos2x) / 2 = (1 / 2) cos2x + 1 / 2
So t = 2 π / 2 = π
To a diameter of 60 cm round tea table with a round tablecloth, tablecloth diameter than tea table 20 cm, this table
How many square meters is this tablecloth larger than the tea table?
3.14 × [(80 / 2) & 178; - (60 / 2) & 178;] = 2198 square centimeters
A cylinder and a cone have the same height and the same bottom. The volume difference between them is 30 cubic decimeters. What are the volumes of the cylinder and the cone
The volume of a cylinder with equal base and equal height is three times that of a cone. This problem can be regarded as the problem of difference times in the Mathematical Olympiad, where the decimal number = difference (multiple-1)
Cone volume = 30 ÷ (3-1) = 15 cubic decimeter
Then the volume of cylinder is 15 × 3 = 45 cubic decimeter
RELATED INFORMATIONS
- 1. The stationery store bought 18 boxes of stationery today, including 540 pens and 840 erasers. If the number of erasers in each box is the same as that of pens, how many erasers are there?
- 2. At the stationery counter of a store, if 16 pencils are sold, the ratio of the number of pencils left to the number of pens is 1:3. If 52 pens are sold again, C At the stationery counter of a store, if 16 pencils are sold, the ratio of the number of pencils left to the number of pens is 1:3. If 52 pencils are sold, the ratio of the number of pencils left to the number of pencils is 2:5. How many pencils are there?
- 3. The number of pencils in the stationery shop is twice that of pens. Every day, 15 pens and 20 pencils are sold out. After a few days, there are still 80 pencils left. How many pens and pencils are there in the stationery shop?
- 4. A shopping mall can make a profit of 2 yuan for each stationery. In order to support the poor mountainous areas, it is now sold to a mountainous school at a 70% discount of the original price. As a result, the profit of each stationery is 0.2 yuan (profit = selling price purchase price). How much is the purchase price of each stationery?
- 5. Each pencil is 0.9 yuan, 2 yuan, 3 yuan, 4 yuan, 5 yuan. Which pencil is cheaper? The number of people who want to score is limited, only one, and those who want to score will come quickly
- 6. Xiao Ming bought several pencils at the price of 1 yuan and 3 pencils, and sold them all at the price of 2 yuan and 5 pencils. If he made 10 yuan, do you know how many pencils he sold?
- 7. Xiao Ming bought three kinds of stationery: pencil, eraser and exercise book. It is known that their numbers are different prime numbers and satisfy the equation: number of pencils * (number of pencils + eraser)
- 8. Li Ming went to the stationery store to buy pencils and erasers for 30 students in the school's art group. It is known that each pencil costs m yuan, and each eraser costs n yuan For two pencils and three erasers, the total payment is RMB
- 9. The stationery store brought in 10 boxes of watercolor pens and 10 boxes of erasers. It costs 4 yuan less to buy watercolor pens than to buy erasers. Each box of watercolor pens costs 8.5 yuan. How much is each box of erasers? Equation! Write the equality!
- 10. According to the price of the stationery box is two fifths less than that of the schoolbag, fill in the quantity relation
- 11. Buy 3 pens in a stationery shop and get 2 free pens, 4 yuan each. How much should I pay for 12 pens?
- 12. The stationery store bought 100 pens at the price of 4 yuan each, and each pen was sold at 6 yuan. When some pens were sold, the remaining pens were sold at a 10% discount. When all pens were sold, the store made a total profit of 188 yuan. How many pens were sold at a 10% discount? Don't use the equation, but use the formula
- 13. I bought a pen, notebook, stationery and schoolbag in the mall
- 14. In order to promote a commodity with the same price, supermarket a, supermarket B and supermarket C cut prices by 20% twice in a row, 40% at a time in supermarket B, 30% at the first time in supermarket C and 10% at the second time. Which supermarket is more cost-effective for customers to buy this commodity A. B. B. C. C. D
- 15. In order to promote a product priced at M yuan, supermarket a, supermarket B and supermarket C cut prices by 20% twice in a row, 40% at a time in supermarket B, 30% at the first time in supermarket C and 10% at the second time. At this time, the most cost-effective supermarket for customers to buy this product is () A. A B. B C. C D. B or C
- 16. Every day, the supermarket bought back a batch of T-shirts from other places with 50000 yuan. Due to the good sales, the mall urgently allocated 186000 yuan to buy back T-shirts that were twice as much as the first time. However, the second time was 12 yuan more expensive than the first time. The mall sold them at the price of 80 yuan. In order to shorten the inventory time, the last 400 T-shirts were sold out at a discount of 6.5% How much is the profit of the Communist Party of China?
- 17. A supermarket used 80000 yuan to purchase a batch of "T-shirts" from other places. Due to the good sales, the supermarket urgently allocated 176000 yuan to purchase "T-shirts" which are twice as much as the last time. However, the second purchase price is 4 yuan more than the first purchase price. The supermarket sells them at 58 yuan per piece, and the remaining 150 pieces are sold out at a 20% discount. How much money has the supermarket made in this business (including two purchases)?
- 18. Xiaoying and several students went to the stationery store to buy exercise books. The stationery store stipulated that if the purchase reached a certain quantity, they could buy them at the wholesale price. So they gathered together 60 yuan to buy them at the wholesale price. In this way, the number of exercise books purchased was 30 more than that purchased at the retail price. If the wholesale price of each exercise book was 45 times of the retail price, what was the retail price of each exercise book How much is it?
- 19. A school logistics staff to a stationery shop to buy test stationery bags for ninth grade students, stationery shop rules a purchase of more than 400, can enjoy a 20% discount. If you buy a ninth grade students, can not enjoy a 20% discount, need to pay 1936 yuan; if you buy 88, can enjoy a 20% discount, also only need to pay 1936 yuan. How many ninth grade students in the school ？
- 20. Xiao Ming and Xiao Gang collect digital cards. Xiao Ming's cards account for 16 / 11 of the total. If he gives 15 cards to Xiao Gang, they will have the same number. How many cards do they have in total?