The given system is
[tex]\begin{cases}x=y-8 \\ -x-y=0\end{cases}[/tex]Step 1: We combine the first equation with the second one
[tex]-(y-8)-y=0[/tex]Step 2: Solve for y.
First, we use the distributive property, then we combine like terms
[tex]\begin{gathered} -y+8-y=0 \\ -2y+8=0 \end{gathered}[/tex]Now, we subtract 8 from each side
[tex]\begin{gathered} -2y+8-8=-8 \\ -2y=-8 \end{gathered}[/tex]Then, we divide the equation by -2.
[tex]\begin{gathered} \frac{-2y}{-2}=\frac{-8}{-2} \\ y=4 \end{gathered}[/tex]Step 3: we solve for x.
[tex]x=y-8=4-8=-4[/tex]Step 4: Give Coordinate, we just have to write down the solutions as coordinates.
[tex](-4,4)[/tex]