The school bought 2700 new books, of which 1200 were distributed to the book corner of each class, and the rest were put into the library of the school. Each bookshelf can hold 260 books at most. How many bookshelves should be placed in total?

six

If you take 12 books from the first shelf to two books on the second shelf
There are two bookshelves. If you take 12 books from the first bookshelf to the second bookshelf, there are as many books on the two bookshelves. If you take 12 books from the second bookshelf, the number of books on the first bookshelf is three times that of the second bookshelf. How many books are there in the two bookshelves? How to calculate?

If you take 12 books from the first bookshelf to the second bookshelf, there are as many books on the two bookshelves; then the number of books on the first bookshelf is 12 * 2 = 24 more than that on the second bookshelf. If you take 12 books from the second bookshelf, the number of books on the first bookshelf is three times that on the second bookshelf

A right triangle ABC. Angle c is 90 degrees, angle B is 30 degrees, ad bisects angle BAC, AC is 2 * root 3, find ad?
The picture is that two triangles are put together to form a triangle,

Angle CAD = 30, AC = 2 * root 3, let CD = x, then ad = 2x, 4x ^ 2 = 12 + x ^ 2, x = 2, hypotenuse ad = 2x = 4

What is the difference between make tea and make the tea
I've checked the meaning of both phrases. What does it mean to make tea with or without the addition of the?
Please don't copy other people's answers. I just saw them in other people's questions

Make the tea
Make tea:

Given that a, B and C are on the same line, m and N are the midpoint of AB and BC respectively, and ab equals 60 and BC equals 40, what is the length of Mn?

It's 50, because m and N are the middle points, so it's easy to figure out the answer
Remember to take my answer,

It's a phrase
The way to
2. What does he look like
3. Poor results:

1 on the way to .
2 What does she look like?
3 make a bad result

The sum of numerator and denominator is 23. After the denominator is increased by 19, a new fraction is obtained. This fraction is reduced to the simplest fraction, which is 15. What is the original fraction?

Can we add countable nouns after some or uncountable nouns

All can be added

sin^4(a/2)-cos^(4a/2)=

sin^4(a/2)-cos^4(a/2)
=[sin^2(a/2)-cos^2(a/2)][sin^2(a/2)+cos^2(a/2)]
=sin^2(a/2)-cos^2(a/2)
=-cosa

How to use English interlanguage?

Your question is too big. There are many contents. Here are some contents about the differences of prepositions for your reference
The difference between about and on
The difference between them is: About refers to talking about something generally or informally, and its content is more common; on refers to discussing something systematically or theoretically, and its content is more formal or serious
He wrote on mathematics
He wrote about the school
It is a book on birds
It's a book about birds
The difference between about, on and with
(1) They can be used to mean "take with you", sometimes interchangeably
I have no money about [on, with] me
(2) Strictly speaking, these three words are different
① About generally refers to small items that you carry with you
Have you a ballpoint pen about you?
② With refers to something larger (or smaller)
He took an umbrella with him
③ On means to take it with you (as in a pocket)
Have you any money on you?
Note: if you use with or about in this example, it may not be on your body, but in your bag
④ Used in the extended sense to express the characteristics of someone or something, usually about
There is something noble about him
He always has his wits about him
We can see something beautiful about the old cottage
The former focuses on external performance, and the latter on internal quality
The difference between about, round and around
(1) It means "in..." The three are often interchangeable
They sat about [round, around] the fire
In modern English, about is rarely used in this case
(2) "Everywhere" is often used interchangeably
He traveled about [round, around] the world
(3) It is used before a number to indicate "about", generally about or around
It costs about [around] ten dollars
There are about 30 bookstores in the city
In British English, round can also be used in the phrase of time
He arrived about [round, around] 5 o'clock
I'll be back about [round, around] lunchtime
(4) To divide something among a group of people, you can use round or around instead of about
Will you hand around [around] the papers?
But it usually doesn't say: will you hand about the papers?
The difference between above and over
(1) Both of them can mean "higher than", over mainly means the top of the vertical, while above does not necessarily mean the top
They built a new room above the garage
Can you see the helicopter above the building?
He stayed at the hotel above the lake
In other words, if it means "above", both can be used; if it doesn't mean "above", it usually uses "above"
(2) Both of them can express "more than" and "more than" of number, quantity, etc For example:
Over [above] 200 people were there
There's nothing in the shop above [over] 50 cents
In modern English, when "above" means "more than", it is mainly used to indicate temperature, height and other conditions comparable with longitudinal standards
It is 2000 ft above sea level
The temperature is two degrees above zero
(3) If it has the meaning of dynamic or covering, it usually uses over instead of above
He flew over to France
Come over and see us later
Cover her over with a sheet
The difference between across, along and through
(1) Both across and through can be used to mean "across" or "through". The former mainly means "across" from the surface of something, involving the concept of "face"; the latter means "through" from a certain space, involving the concept of "body"
He walked across the road carefully
He walked through the forest alone
Sometimes across can also be carried out in the body, but it is still different from through: the former means from one end of a body to the other, and the latter means through both ends
He walked across the hall
He walked through the hall
(2) "Along" means "along". It is usually used for narrow things
I saw him running along the road
We walked along the river
(3) Note the following idioms:
① When used with abstract nouns, it means "through"
He became rich through hard work
② In American colloquial English, from... Through can be used to mean "from In this case, neither along nor across is needed
We work from Monday through Saturday
The difference between after and in
(1) Can be used with a period of time to indicate "in "After" is usually used in conjunction with the past tense because it starts from the past time, while "in" is usually used in the future or in sentences with future meaning
He came back after three days
I'll come back in three days
I think he can come back in three days
(2) In addition to a period of time, after can also be used with a little time, which can be used in the future tense
He will arrive after five o'clock
(3) After can be used with some nouns indicating activities to indicate "in After "(Note: in cannot be used in this way)
After school after the meeting
After liberation after one's graduation
The difference between after and behind
Both can mean "in The differences are as follows:
(1) After is mainly used for time or order, behind is mainly used for position
He decided to leave after lunch
Summer comes after spring
The hospital is behind the post office
"Behind" is sometimes used to express "later than" and is mainly used in the idiom "behind time"
The train was 20 minutes behind time
(2) After refers to pursuit, seeking, imitation, etc., while behind refers to behind, support, backwardness, etc
The police are after her
Many young people are after her
We are behind you completely
He is behind the others in math
The difference between ■ along and between
(1) "Among" is generally used for three or more "in The object of "middle" is usually a noun or pronoun which means a general quantity or has plural (or collective) meaning
They hid themselves among the trees
I found it among a pile of old books
[note] among is also used in the following cases:
① It is used to draw out the comparison range of the highest level
The book is the best among the modern novels
② It means "yes One of them
I was along the first to come
Paris is along the largest cities in the world
(2) "Between" generally refers to the two, and its object is usually a noun or pronoun indicating the two, or two people or things connected by and

The school bought 2700 new books, of which 1200 were distributed to the book corner of each class, and the rest were put into the library of the school. Each bookshelf can hold 260 books at most. How many bookshelves should be placed in total?