Number of copies = (surplus+deficit) ÷ twice the distribution difference

Number of copies = (big profit-small profit) ÷ the difference between the two distributions.

Number of copies = (big loss-small loss) ÷ Difference between two distributions

example

The teacher borrowed some science and technology books from the library and distributed them to several students. If each student is divided into three books, there are two more. If everyone is divided into four parts, there are six parts missing. Q: How many students are studying? How many books did the teacher borrow?

Dial:

As can be seen from the title, the second method has 4-3= 1 (book) per person than the first method, so the number of books divided is changed from 2 more to 6 less, so the total difference is 2+6=8 (book), that is to say, if there are 8 more books, each person can be assigned to 1 book, so the number of people reading books is 8.

(This is the most basic example, and the rest can be done with formula sets. )