Addition elimination

Question

The system when solved is:

y — x = 12

y + x = -26

Answer 1

y - x = 12

y + x = -26

If we add the 2 equations together...

y + y = 2y

-x + x = 0

12 + (-26) = -14

Putting that all together...

2y = -14 (we don't say + 0 because that would be silly).

2y/2 = -14/2

y = -7

Substitute into either equation...

-7 + x = -26

x = -19

(-19,-7)

Let's check...

-7 - (-19) = 12

-7 + 19 = 12

12 = 12

0 = 0

-7 + -19 = -26

-26 = -26

0 = 0

Hey, our point works for both lines, so it's where they meet and thus our solution.

Answer 2

I am not sure what you want.

If you add the 2 equations, you get: 2y = -14 which means y = -7 and x = -19.