Solving a System of 2 Equations Using the Addition/Subtraction Method

To solve a system of linear equations using the addition/subtraction method, both equations should first be written in the form Ax + By = C.

Let's take a look at the system of equations below:

   x + 2y = 3

15x - 2y = 29

As shown below, adding the equations together eliminates one of the variables. In this case, it's the y-variable that is eliminated..

Now we're left with 16x = 32. Solving for x, we get x = 2.

Substitute 2 for the x-variable in either of the original equations and solve for y. (We'll use the equation x + 2y = 3 because it looks simpler.)

x + 2y = 3
2+2y = 3
2y = 1
Y = 1/2
So we claim that the solution to the system is (2, 1/2) Now check this answer in both of the original equations:

Therefore, the solution to the system is (2, 1/2)