Question

How do you solve the system `-2x -8y = 4` and `5x-5y=20`?

Answer 1

`(x,y) = (26/5, -6/5)`
Note: As stated in the comments, this question has been modified. If the original intent was correct (2 equations in 4 variables), no solution is possible.

Explanation:

[1]`color(white)("XXXX")` `-2x-8y=4`
[2]`color(white)("XXXX")` `5x-5y =20`

Simplifying [1] by dividing by `(-2)`
[3]`color(white)("XXXX")` `x+4y = -2`
Simplifying [2] by dividing by `5`
[4]`color(white)("XXXX")` `x-y= 4`

Subtract [4] from [3]
[5]`color(white)("XXXX")` `5y = -6`
Divide by `5`
[6]`color(white)("XXXX")` `y = -6/5`

Substituting `(-6/5)` for `y` in [4]
[7]`color(white)("XXXX")` `x - (-6/5) = 4`

[8]`color(white)("XXXX")` `x =26/5`