Concept:

An equation with an unknown number is called an equation. (An equation is not necessarily an equation, but an equation must be an equation. ) The value of the unknown that makes the left and right sides of the equation equal is called the solution of the equation. The process of solving an equation is called solving an equation. Nature:

Add and subtract the same number on both sides of the equation, and the left and right sides are still equal.

Both sides of the equation are multiplied by the same number or divided by the same number that is not 0, and the left and right sides are still equal.

Steps to solve problems with column equations:

(1) Find the unknown number, which is represented by the letter X;

(2) Analyze the quantitative relationship in practical problems, find out the equivalence relationship and make equations;

(3) Solve the equation and test the answer.