Use addition to solve the system of linear equations. include all of your work in your final answer.
-x - y = 4
x + 2y = 4

x = - 12, y =8

Step-by-step explanation:

The given system of linear equations is expressed as

-x - y = 4 - - - - - - - - - - - - - - 1

x + 2y = 4 - - - - - - - - - - - - - - 2

The first step is to eliminate x by adding equation 1 to equation 2. It becomes

-x + x + - y + 2y = 4 + 4

y = 8

Substituting y = 8 into equation 1, it becomes

-x - 8 = 4

We would add 8 to the left hand side and the right hand side of the equation. It becomes

-x - 8 + 8 = 4 + 8

-x = 12

Dividing the left hand side and the right hand side of the equation by -1, it becomes

- x/ - 1 = 12 / - 1

x = - 12