An equation can be true or false. An example of a true equation is . An example of a false equation is . 

An equation can have a letter in it to represent a value, for example, . This equation is false if is 3, because does not equal 8. This equation is true if is 7, because .

A letter in an equation that represents an unknown value is called a variable. In , the variable is . A number that can be used in place of the variable that makes the equation true is called a solution to the equation. In , the solution is 7.

When a number is written next to a variable, it means the number and the variable are being multiplied. For example, means the same thing as . A number written next to a variable is called a coefficient. If no coefficient is written, the coefficient is 1. For example, in the equation , the coefficient of is 1.