1, the quantitative relationship of "one profit and one loss" problem: (profit+loss) ÷ the difference between two distributions = the total number of objects participating in the distribution twice.

2. The quantitative relationship of the problem of "two losses": the difference between two losses ÷ the difference between two distributions = the total number of objects participating in the distribution twice.

3. The quantitative relationship of the "two benefits" problem: the difference between the two benefits ÷ the difference between two distributions = the total number of objects participating in the distribution twice.

Example 1. The kindergarten teacher gives pears to the children. If each child gets four pears, there will be nine more. If everyone is divided into five parts, six parts are missing. How many children are there? How many pears?

Example 2: Xiaoming goes to buy exercise books. The money he paid the clerk bought four more copies, 1 yuan, and six copies were sent to 2 yuan. How much does Xiao Ming pay the clerk? How much is each exercise book?

Example 3: The teacher awarded some pencils to three good students. Five cigarettes per person is four more, and seven cigarettes per person is four less. How many pencils does the teacher have? How many miyoshi students won the prize?

Example 4: The kindergarten teacher gave the children a basket of apples. If five students are given to each large class, the rest are10; If the students in a small class are divided into eight, two are missing. As we all know, there are three more students in the big class than in the small class. How many apples are there in this basket?

Example 5: Xiaojun's grandmother bought a basket of pears and distributed them to the whole family. If Xiaojun and his sister are divided into five parts, the rest are divided into two parts, and there are four parts; If a small army is divided into six and the rest into four, the difference is 12. How many people are there in Xiaojun's family? How many pears are there in this box?