[tex] \bf \begin{cases}
x-2y=-7\\
x-y=9\implies \boxed{x}=9+y
\end{cases}
\\\\\\
\stackrel{\textit{substituting \underline{x} in the first equation}}{\boxed{9+y}-2y=-7}\implies -y=-16
\\\\\\
y=\cfrac{-16}{-1}\implies y=16\\\\
-------------------------------\\\\
\stackrel{\textit{and substituting \underline{y} in the first equation}}{x-2(16)=-7}\implies x-32=-7\implies x=25
\\\\\\
~~~~~~~~~~~~~~~~~~~~~~~~~~~~(\stackrel{x}{25}~~,~~\stackrel{y}{16}) [/tex]
