Solve the system of linear equations by elimination. −x+y=4
x+3y=4

please explain

y = 2   x = -2

Step-by-step explanation:

-x + y = 4

x + 3y = 4

Since x and -x are opposite, we can use the system of elimination

To do that, we add the first equation and the second equation together

-x + y = 4

      +

x + 3y = 4

      ↓

4y = 8

Now we solve for y

4y = 8

Divide both sides by 4

y = 2

Since we now know y, we can solve for x by substituting y for 2 in one of the equations.

x + 3y = 4

Substitute y for 2

x + 3 (2) = 4

x + 6 = 4

Subtract 6 from both sides

x = -2

Hope I helped! And sorry if I repeated somethings.

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