An equation is a mathematical statement that has two expressions separated by an equal sign. The expression on the left side of the equal sign has the same value as the expression on the right side.

One or both of the expressions may contain variables. Solving an equation means manipulating the expressions and finding the value of the variables.

An example might be:x - 3 = 5
To keep an equation equal, we must do exactly the same thing to each side of the equation. If we add (or subtract) a quantity from one side, we must add (or subtract) that same quantity from the other side.
to solve this equation we would add 3 to both sides. The equation would become x - 3 + 3 = 5 + 3. This becomes x = 5 + 3 or x = 8.