The ratio of story books to science and technology books in the book corner of a class is 1:8. Later, the students bought five more story books, so the ratio of story books to science and technology books is 1:4. How many books were there in the book corner?

Five story books, 40 science and technology books,

The number ratio of science and technology books to story books in the library is 2:3. In the morning, a batch of newly purchased science and technology books are set in the library, and after sorting, the number ratio of science and technology books to story books is 10:9. In the afternoon, the number ratio of science and technology books to story books is 5:6. Only 100 more science and technology books have been purchased than story books How many science books and story books are there?

The original ratio of science and technology books to story books is: 2:3 = 6:9. In the morning, a batch of newly purchased science and technology books are set up in the library. After sorting out, the ratio of science and technology books to story books is 10:9. Therefore, the purchase of science and technology books is 10-6 = 4. In the afternoon, the newly purchased story books and story books are put into the library. At this time, the ratio of science and technology books to story books is: 5:6 = 10:12; the purchase of story books is 12-9 = 3 (copies), so the total number was 100 × (4-3) × (6 + 9) = 1500 (copies); a: there were 1500 science and technology books and story books in the library

How many cubic meters is a ton

If it's water, it's a cube
This is common sense
Other things will be calculated according to the specific gravity
For example, 1 ton of iron is less than 1 cubic meter, and cotton is more than 1 cubic meter

The fruit shop shipped 700 cases of apples and pears. The number of cases of apples is 2 / 5 of that of pears?
For ideas, the answer should be complete. A fraction of the semicolon should have "Fen", otherwise I don't understand (∩)_ ∩)

Pears: 700 divided by (1 + 2 / 5) = 500 cases
Apple: 700-500 = 200 cases

A half to a fifth is a quarter to an X
It's a detailed process

A half to a fifth is a quarter to an X
2 / 2 x = 1 / 5 * 1 / 4
2 x = 1 in 20
X = 1 / 20 ／ 1 / 2
X = 1 / 10
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How do you convert these into singular and plural forms?
1.These are Alice's parents.
2.This is your an orange.
3.Those are my watches.
4.This girl is my cousin.

1.This is Alice's parent.
2、These are your oranges.
3.That is my watch.
4.These girls are my cousins
The plural of these two demonstrative pronouns is these those
Everything else is plural

Teachers and students of class 6 (1) and class 6 (2) rent cars to go to the summer camp. If each car takes 20 people, then 20 people have no seats. If each car takes 25 people, then it is just full
How many cars are there in class 6 1 and class 6 2? Quick, urgent. Use equation to solve

20X+20=25X
5X=20
X=4
4 cars

Video: Verification: the square difference of two adjacent natural numbers must be odd

Suppose one number is n, then the other number is n + 1
The square of (n + 1) is equal to the square of N + 2n + 1
Square of (n + 1) - square of n = square of N + 2n + 1-square of n = 2n + 1
No matter what number n is, 2n is even and 2n + 1 is odd

Simplification: cN0 + 1 / 2cn1 + 1 / 3cn2 +... + 1 / (n + 1) CNN

1/(k+1)C(n,k)
=n!/(n-k)!k! * 1/(k+1)
=n!/(n-k)!(k+1)!
=(n+1)!/(n+1-k-1)!(k+1)! *1/(n+1)
=C(n+1,k+1)*1/(n+1)
therefore
Cn0+1/2Cn1+1/3Cn2+...+1/(n+1)Cnn
=1/(n+1)C(n+1,1)+1/(n+1)C(n+1,2)…… +1/(n+1)C(n+1,n+1)
=1/(n+1) [C(n+1,1)+C(n+1,2)…… +C(n+1,n+1)]
=1/(n+1)*(2^(n+1)-1)
Because (1 + 1) ^ n = C (n, 0) + C (n, 1) + +C(n,n)
So C (n + 1,1) + C (n + 1,2) +C(n+1,n+1)=(1+1)^(n+1)-C(n+1,0)=2^(n+1)-1
So cN0 + 1 / 2cn1 + 1 / 3cn2 +... + 1 / (n + 1) CNN = 1 / (n + 1) * (2 ^ (n + 1) - 1)

Four minibuses and one bus carry the same number of people. One bus and one minibus can seat 75 people
Four minibuses and one bus carry the same number of people. One bus and one minibus can seat a total of 75 people. How many people can each minibus and bus seat?

A bus and a van are equivalent to five vans. 75 divided by 5 equals 15, so bus 15x4 = 60 (people) and van 15 people

The ratio of story books to science and technology books in the book corner of a class is 1:8. Later, the students bought five more story books, so the ratio of story books to science and technology books is 1:4. How many books were there in the book corner?