To solve a system of equations by addition, also called elimination, the goal is to cancel out one of the variables by adding the equations together. However, in some cases, you will need to multiply one or both of the equations by a number in order to create a scenario where one of the variables will cancel out when the equations are added together. As long as you cancel a variable out, you will be able to add the equations together and solve for the variable. If you find one variable, you can find the other one easily.