1. The stock of white paper in a store is twice that of red paper. If 300 pieces of red paper and 400 pieces of white paper are sold out every day, after a few days, there are 1400 pieces of red paper left. How many pieces of white paper are in stock? Twenty years ago, my father was six times as old as Xiaoling. Today, my father is two times as old as Xiaoling 3. The ratio of the number of young pioneers of team a and team B is 7:3. If 30 people are transferred from team a to team B, the ratio of team a and team B to admit defeat is 3:2. How many people are there in team B? 4. The distance between a and B is 340km. Two buses a and B start from two places at the same time and travel opposite each other. After four hours, a and B meet. It is known that the speed of a and B is 8:9. What is the speed of B?

1. The stock of white paper in a store is twice that of red paper. If 300 pieces of red paper and 400 pieces of white paper are sold out every day, a few days later, all the red paper is sold out, and there are 1400 pieces of white paper left. How many pieces of white paper are in stock?
If x pieces of white paper are in stock, then x / 2 pieces of red paper are in stock
The number of days of red paper sold out is (x / 2) / 300 = x / 600
When the red paper is sold out, the white paper will buy 400 * x / 600 = 2x / 3 pages
So according to the meaning of the title
x-2x/3=1400
x/3=1400
x=4200
That is 4200 pieces of white paper in stock
Twenty years ago, my father was six times as old as Xiaoling. Today, my father is two times as old as Xiaoling
Let Xiaoling's age be X this year, then Xiaoling's age was x-20 20 20 years ago, so father's age 20 years ago was 6 (x-20)
6(x-20)+20=2x
6x-120+20=2x
4x=100
x=25
Xiaoling is 25 years old this year
3. The ratio of the number of young pioneers of team a and team B is 7:3. If 30 people are transferred from team a to team B, the ratio of team a and team B to admit defeat is 3:2?
If team B has X members, team a has 7x / 3 members
(7x/3-30)/(x+30)=3/2
14x/3-60=3x+90
5x/3=150
x=90
That is, the original number of team B is 90
4. The distance between a and B is 340km. Two buses a and B start from two places at the same time and travel opposite each other. After four hours, a and B meet. It is known that the speed of a and B is 8:9. What is the speed of B?
Suppose the speed of car B is x, then the speed of car a is 8x / 9
4*(x+8x/9)=340
4*17x/9=340
x=45
That is, the speed of car B is 45 km / h

The electricity consumption in August is 98% of that in July, which is ()% less than that in July

A batch of books came in the bookstore, and they sold 30% for the first time. The next day, they sold 250 more than the first day, and there were 100 left. How many books were there? Can you give me the solution?

Suppose there were x books
First sale: 30% X
Sell the next day: 30% x + 250
According to the meaning of the question, the equation is: 30% x + 30% x + 250 + 100 = X
350=0.4x
x=875
There were 875 books
However, there is a problem with this question. It is impossible to buy 875x30% = 262.5 copies on the first day?

Six (1) class students participated in the cleaning, the number of participants is not a quarter of the number of participants, and then there are two students to participate
The number of students in class 6 (1) who took part in the clean-up was one fourth of those who did not. Later, two students took the initiative to take part in the clean-up, and the actual number was one third of those who did not. How many students took part in the clean-up?
How to do, all right!!!

There were X students participating in the cleaning
（X+2）/（4X-2）=1/3
X=8
A: there were eight

The original 15 students of class one took part in the clean-up, and then 2 students took part. The actual number of students was 13 of the rest. How many students took part in the clean-up?

2 △ 11 + 3-15) × 15 = 2 △ 120 × 15 = 8 (people). A: 8 students participated in the cleaning

One fifth of the students in the sixth year class took part in the general cleaning, and later two students in the class took the initiative. The actual number of students who took part in the general cleaning was the same as those who did not
How many students participated in the cleaning? The equation

If x people participate in the general cleaning, the total number is 5x. Then: 4x-2 = 3 (x + 2), you can get x = 8
As a result, there are 40 students in the class, of whom 8 participated
If the answer is correct,

Six year class originally planned to take 20% of the class to participate in the general cleaning. Later, six students took the initiative to participate in the general cleaning. The actual number of students participating in the general cleaning is 50% of the rest?

6÷【50/（1+50）-20%】
=6÷【1/3-1/5】
=6÷2/15
=45 people

Class five (1) had a weekend cleaning. One sixth of the students swept the floor. Later, two more students took part in the cleaning. At this time, the number of people sweeping the floor accounted for one fifth of the class. How many people are there in class five (1)?

There are five (1) classes with X people
1/6X+2=1/5x
1/5x-1/6x=2
1/30x=2
x=60
A: there are 60 students in class five (1)

Elementary school sixth grade Olympiad mathematical problems and answers 100

Take 1 / 10 apart, 1 / 10 = 99 / 100 by 98 / 99 by 97 / 98. Take 11 / 12 by 10 / 11, 1 / 2 by 3 / 4 by 5 / 6 by 7 / 8 by 8 / 9 by 9 / 10 by 10 / 11 by 11 / 12. Take 99 / 100 = 1 / 2 by 3 / 4 by 5 / 6 by 7 / 8 by 9 / 10 by 1 / 10. Because 1 / 2 by 3 / 4 by 5 / 6 by 7 / 8 by 8 / 9 by 9 / 10 must be less than 1, so 1 / 2 by 3 / 4 by 5 / 6 by 7 / 8 by 8 / 9 by 9 by 1 / 10 must be less than 1 / 10, so a is smaller than B

The number of trees planted in class one is 100 more than 3 / 10 of the total number, and the number of trees planted in class two is 50 less than 3 / 5 of the total number
A store has 12 yuan per kilogram of type a sugar, 8 yuan per kilogram of type B sugar and 6 yuan per kilogram of type C sugar. One day, the kilogram ratio of type A and type B sugar is 3:8, and the kilogram ratio of type B and type C sugar is 2:1. The total income is 2170 yuan, At this time, the basket still has 44 kg. How many kg is the net weight of this basket? How many kg are they sold?
For a basket of apples, first take out 140, and then take out the remaining 60%. At this time, the remaining apples are just 1 / 6 of the original total. How many apples were there in the basket?
Party A, Party B, Party C and Party D work together on a batch of parts. Party A does half of the total work of the other three people, Party B does one third of the total work of the other three people, Party C does one fourth of the total work of the other three people, and Party D does 390 pieces of work
There are 380 tons of grain in the two warehouses. Warehouse a transports 2 / 5 of the stored grain, and warehouse B transports 1 / 3 of the stored grain. At this time, the remaining grain in the two warehouses is just the same. How many tons of grain did warehouse A and warehouse B store
It takes 6 hours for a to complete a section of the road, while the speed of B is 20% faster than that of A. It takes several hours for B to complete this section of the road

1. Suppose the total number is x, then the first class plants (3 / 10 * x + 100) trees. The second class plants (3 / 5 * x - 50) trees. (3 / 10 * x + 100) + (3 / 5 * x - 50) = x x x = 5002. Suppose that the three kinds of sugar sell 3x, 8x, 4x g respectively. 12 * 3x + 8 * 8x + 6 * 4x = 2170, x = 17.5, the first kind sells 52.5 g, the second kind sells 140 g, the third kind sells 52.5 G