By bus, 40% of the total number of passengers get off the bus, and another 9 people come up. This is one twentieth more passengers than before. How many people are there in the bus? The clothing store buys 100 sets of sportswear, each of which costs 200 yuan, and sells them at a price of 50% of the expected profit. When 60% of the sportswear is sold, the rest of the sportswear is sold at a discount. After 100 sets of sportswear are sold out, the expected profit is reduced by 18%. How much discount is the clothing sold

By bus, 40% of the total number of passengers get off the bus, and another 9 people come up. This is one twentieth more passengers than before. How many people are there in the bus? The clothing store buys 100 sets of sportswear, each of which costs 200 yuan, and sells them at a price of 50% of the expected profit. When 60% of the sportswear is sold, the rest of the sportswear is sold at a discount. After 100 sets of sportswear are sold out, the expected profit is reduced by 18%. How much discount is the clothing sold

1. Solution: 9 △ [(1 + 1 / 20) - (1-40%)] = 9 △ (21 / 20-3 / 5) = 9 / 20 = 20
Let y be a fold
（100×60%）×（200×50%）+（100×40%）×[(200+200×50%)y/10-200]=100×200×(50%-18%)
∴y=7

For example, AB equals ad, BC equals CD, point P is any point of a straight line, (different from a, c), and P, B, PD

Connect AD and BC, then:
(1)∠A=∠C
(2)∠D=∠B
(3)∠APD=∠CPB
(4)AP=CP
Then:
If APD and CPB are congruent, Pb = PD

1. Equations x + y + 2 = 18
1/2(x+y)=z
x-y=1/3z
Two hundred and ninety-nine Wen money sweet fruit bitter fruit buy one thousand sweet fruit nine eleven Wen
Seven bitter fruits and four Wen
I just hate the process

1. Addition and subtraction elimination method!
X=3/48 Y=3/40 Z=8
2、
There are 9x sweet fruits and 7Y bitter fruits
9x+7y=1000
11x+4y=999
Solution
x=73 y=49
so
Sweet fruit is 9 * x = 657, bitter fruit is 7 * y = 343

1) If the two sides m and N of an isosceles triangle satisfy the equation | M-N + 2 | + (2m + 3n-11) & sup2; = 0, find the perimeter of the isosceles triangle
2) It is known that in quadrilateral ABCD, ad ∥ BC, BD bisection ∥ ABC, ∥ A: ∥ abd = 4:1
1. Find the degree of ∠ a
2. If △ BCD in the graph is a right triangle, find the degree of ∠ C

(1) M-N + 2 = 0 (2) 2m + 3n-11 = 0, M = 1, n = 3. Because the sum of the two sides of the triangle is greater than the third side, n can only be the length of the waist of the triangle, so the perimeter is 3 + 1 + 3 = 72

There is only one car for a team member to go from a to B, which is 18 kilometers away. Divide all the team members into two groups: group A and group B. let group a take the bus first, group B walk, and set out at the same time. Group A gets off at C on the way, and then walk on. The car turns back to group B and arrives at B at the same time. If the speed is 60 km / h, the walking speed is 4 km / h, C the distance between the two places and how many kilometers do the two groups walk?
Write out the process with the solution of binary linear equation, O (n)_ n)o

I don't know if it's hard for you
Suppose: AC is x, CB is y
（X-Y/4*60）4=X/60+Y/4
X+Y=18
This system of equations can be obtained

Square ABCD is a ring road. It is known that the speed of a car on AB is 90 km / h, that on BC is 120 km / h, that on CD is 60 km / h, and that on Da is 80 km / h. If a car starts from a point P on DA at the same time, they will meet at the midpoint of ab, They will meet at a point n on ab. then the distance between a and N is several times that between N and B
But be quick

To do this problem, you need to draw a picture first. After drawing the picture, find the position of point P according to the known conditions. Let each side of the square be 1, and the distance from point P to point d be X. according to the principle of equal time from starting to meeting, make the equation: (1-x) / 80 + 1 / 2 * 1 / 90 = x / 80 + 1 / 60 + 1 / 120 + 1 / 2 * 1 / 90

In 2012, a company plans to broadcast 300 minutes of advertising in two TV stations. It is known that the advertising fees of the two TV stations are 500 yuan / min and 200 yuan / min respectively, and the total advertising expenses of the company is 90000 yuan. It is estimated that the two TV stations will bring 3000 yuan / min and 2000 yuan / min respectively, How many minutes should the company broadcast advertisements in two TV stations? How many million yuan of total revenue will the two TV stations bring to the company in 2012?

1. If TV station a plays X minutes and TV station B plays y minutes, then
Equations: 500X + 200y = 90000
X+Y=300
The solution is: x = 100, y = 200
2. Total income: 0.3 * 100 + 0.2 * 200 = 700000 yuan

Given M & # 178; + 2m-1 = 0, find the value of M & # 178; + M & # 178 / 1
Remember to write ∵

M & # 178; + 2m-1 = 0 can be transformed into m ^ 2-1 = - 2m. Obviously, m ≠ 0 can be obtained by dividing both sides by M;
M-1 / M = - 2, then square both sides to get m ^ 2-2 + 1 / m ^ 2 = 4
So M & # 178; + 1 / M & # 178; = 6
Ask questions

There are 700 grams of salt water with a concentration of 2.5%. In order to make salt water with a concentration of 3.5%, it needs to be evaporated______ A gram of water

700-700 × 2.5% / 3.5% = 700-17.5% / 3.5%, = 700-500, = 200 (g), answer: 200 g of water will be evaporated; so the answer is: 200

Please teachers and students to answer this Primary School Mathematical Olympiad
A manuscript, a copy alone 3 hours to complete 1 / 4, B then a copy alone 4.5 hours to complete the remaining 1 / 3?

The key is to first analyze such a problem: the title only requires to copy this manuscript within 10 hours, how can party A and Party B arrange the cooperation time at least? We can think of: let the efficient people work for 10 hours, and then let the inefficient people cooperate for the unfinished part, so that the cooperation time can be at least