We have a system of linear equations:
[tex]\begin{gathered} x=-8y \\ -x+y=18 \end{gathered}[/tex]We have to solve by substitution. This is the most appropiate method a s we already have one of the variables in function of the other.
Then, we can replace x in the second equation as:
[tex]\begin{gathered} -x+y=18 \\ -(-8y)+y=18 \\ 8y+y=18 \\ 9y=18 \\ y=\frac{18}{9} \\ y=2 \end{gathered}[/tex]With the value of y, we can calculate x from the first equation:
[tex]x=-8y=-8\cdot2=-16[/tex]Answer: x=-16 and y=2
