Mathematics application problem in grade two of junior high school~ Do me a favor with math. It's hard 1. A container is filled with 20 thousand pure alcohol. The first time you pour out a certain amount of pure alcohol, fill it up with water. The second time you pour out the same number of liters, the remaining pure alcohol in the container is 5 liters. How much is it each time? 2. Not long ago, in the reconstruction of a street in the urban area, a 3000 meter long blind road was planned to be built for the disabled. According to the planning and design requirements, construction personnel were increased, and the number of blind roads built every day was increased by 15 meters compared with the original plan. As a result, it was completed 10 days in advance. How many meters of blind roads are actually built every day?

20-x - (20-x) * x / 20 = 5, the solution is x = 10
3000 / x-3000 / (15 + x) = 10, the solution is x = 60

1. Given that y and X are in positive proportion, and x = 2, y = 15, then the functional relationship between Y and X is——
2. Given a function y = kx-2, please add a condition that y decreases with the increase of X

1. Let the functional relation between Y and X be y = KX (in positive proportion)
Then 15 = 2K
k=7.5
The functional relation between Y and X is y = 7.5x
2. When k

In the same rectangular coordinate system, the approximate position of the image of the first-order function y = kx-k2-1 and the inverse scale function y = KX is ()
A. B. C. D.

A. ∵ from the first and third quadrants of the image of the inverse proportion function, we can see that the image of K ＞ 0, ∵ k2-1 ＜ 0, ∵ primary function y = kx-k2-1 passes through the first, third and fourth quadrants, so this option is wrong; B, ∵ from the second and fourth quadrants of the image of the inverse proportion function, we can see that the image of K ＜ 0, ∵ k2-1 ＜ 0, ∵ primary function y = kx-k2-1

Do me a favor and solve a math problem
1. A cylindrical cup with a bottom radius of 10 cm is filled with water. A conical plumb with a bottom radius of 4 cm is immersed in the water. When the plumb is taken out of the cup, the water surface in the cup drops by 2 cm. What is the height of the plumb
2. If the height of a cylinder increases by 2 decimeters, the volume will increase by one tenth, and the surface area will increase by 6.28 square decimeters. What is the volume of the original cylinder?
3. The weight ratio of the two bags of sugar is 4:1. Take 10 kg sugar from bag a and put it into bag B. at this time, the weight ratio of the two bags is 7:5?

1. The volume of the cylindrical water cup falling 2cm = the volume of the vertebral body
Volume of cylinder = base area * height
Volume of cone = bottom area * height / 3
Put in the numbers
2. The volume of the cylinder is equal to the area of the bottom * the area of the high bottom
Surface area = bottom area + side area
Side area = π * diameter * height
With the increase of height, the bottom area remains unchanged, but only the side area changes
3. A proportional equation is enough
A: B = 4:1
(A-10): (B + 10) = 7:5

It costs 7 yuan to buy 2.5kg of apples. The ratio of the total price to the quality of the apples is (), and the ratio is (). Fill in the blanks,

It costs 7 yuan to buy 2.5kg apples. The ratio of total price to quality is (7:2.5), and the ratio is (2.8). This ratio represents (unit price)

Given that a and B are reciprocal to each other, what is the result of a / b,

It is known that a and B are reciprocal,
So a × B = 1
So a 2 / 2 A / b 5 / 2
=2 / a × 5 / b = 10 / AB
=1 in 10

A supermarket pays business tax at 5% of its total income in July, with a total business tax of 1590 yuan. What is the turnover of the supermarket in July?

What is the turnover of the supermarket in July
1590 / 5% = 31800 yuan

There is a job that needs to be completed within the specified date. If Party A does it alone, it will be completed on schedule. If Party B does it alone, it will be 3 days beyond the specified date. Now Party A and Party B work together for 2 days, and the rest of the work will be done by Party B alone, it will be completed on schedule. How many days is the specified date?

Suppose the specified date is x days, then it takes X days for Party A to complete the work alone, and (x + 3) days for Party B to complete the work alone. According to the meaning of the question, the equation is: 2x + 2x + 3 + X − 2x + 3 = 1. The solution is: x = 6. The test shows that x = 6 is the solution of the original equation. Answer: the specified date is 6 days

Let's do you a favor~
Let a = (1,2,3), what is the difference between M = {X / X belongs to a} and N = {X / X is contained in a}?
2 let B and C be finite sets, the number of elements in B is m, the number of elements in C is n, and N > M. if a is contained in B, a is contained in C
How many elements are there at least in a?
What is the maximum number of elements in a?

1. X in M should mean that x in n is a set
2. At least there is no empty set
At most M are equal to B

The purchase price of a store is reduced by 8% while the selling price remains unchanged. As a result, the profit of the store can be increased by 10%. What is the original profit margin?

Let m be the purchase price of the store and n be the selling price. According to the question, n-mm × 100% + 10% = n-0.92m0.92m × 100%, the solution is n = 1.15m, so the original profit margin is n-mm × 100% = 1.15m-mm × 100% = 15%

1. Given that y and X are in positive proportion, and x = 2, y = 15, then the functional relationship between Y and X is—— 2. Given a function y = kx-2, please add a condition that y decreases with the increase of X

In the same rectangular coordinate system, the approximate position of the image of the first-order function y = kx-k2-1 and the inverse scale function y = KX is () A. B. C. D.