An equation is a mathematical sentence that uses the equal sign = to show two expressions are equivalent. The expressions can be numbers, variables, constants, or combinations thereof. There are many ways to solve an equation. One way is by using a method called guess-and-check. A guess-and-check method involves guessing a value for the variable in an equation and checking to see if it is the solution by substituting the value in the equation. If the resulting equation is a true statement, then the value you guessed is the solution of the equation. If the equation is not a true statement, then you adjust the value of your guess and try again, continuing until you find the solution. Another way to solve an equation is by working backward. In this method, you begin at the end and work backward toward the beginning.

A solution of an equation is a value for the variable that makes the equation true. To determine the solution of an equation, you will use the Properties of Equality.

In this image, you will see how different mathematical operations are used to undo or evaluate each other. (WHY? you will want to solve for a variable by getting it by itself)