[tex]\begin{gathered} -x+y=-1 \\ 2x-y=3 \end{gathered}[/tex]
To solve the given system of equations for substitution you:
1. Solve in one of the equations a variable.
For the given options the one that is correct is solve the first equation for y, by adding x to both sides:
[tex]\begin{gathered} -x+x+y=-1+x \\ y=-1+x \end{gathered}[/tex]
