整式加减是初中数学的重要内容,它是为我们后面学习方程及不等式做准备的.近几年,这部分内容出现了许多说理题.现举几例说明这类问题的解决方法.例1李老师给学生出了一道题: The addition and subtraction of integers is an important part of junior high school mathematics. It is a preparation for us to learn about equations and inequalities. In recent years, there have been a lot of arguments in this part. There are several examples to illustrate the solution to this type of problem. Example 1 Teacher Li gave the students a question: