This addition rule is useful for solving equations like this:

\(\large\mathsf{ x − 8 }\) = \(\large\mathsf{ 12 }\)

But there are other kinds of equations for which the addition rule doesn't help us to solve the equation. For example:

\(\large\mathsf{ 2 x }\) = \(\large\mathsf{ 8 }\)

In an equation like this, it wouldn't help to add something to both sides of the equation, so we need another operation to help us solve the equation. Remember, to solve an equation, we always want to get the unknown by itself. In the previous example, the unknown is not by itself; it is being multiplied by 2. So we don't know what the value of x is. We only know what the value of 2x is. To remove the 2 from the x, we need to use the division rule for equations: