Question

Solve this system by substitution (Pls answer step by step so I can understand thank you!)

Answer 1

-3

Explanation:

1) -x-y = 9

2) -3x+y = 3

By adding 3x to each side on equation #2, you get that y = 3+3x.

Now, we can substitute the value of y into the second equation. If you do this, you will get that
`-x-(3+3x)=9`.

Simplifying gives you:
`-4x-3=9`

Adding three to both sides:
`-4x=12`

And finally dividing by negative four:
`x=-3`

You will get x = -3