[tex]\bf \begin{cases} y=6x+9\\ 27x-3y=-81 \end{cases}~\hspace{10em}\begin{array}{|c|ll} \cline{1-1} slope-intercept~form\\ \cline{1-1} \\ y=\underset{y-intercept}{\stackrel{slope\qquad }{\stackrel{\downarrow }{m}x+\underset{\uparrow }{b}}} \\\\ \cline{1-1} \end{array} \\\\\\ y=\stackrel{\stackrel{slope}{\downarrow }}{6}x+9 \\\\\\ 27x-3y=-81\implies 27x+81=3y\implies \cfrac{27x+81}{3}=y \\\\\\ \cfrac{27x}{3}+\cfrac{81}{3}=y\implies \stackrel{\stackrel{slope}{\downarrow }}{9}x+27=y[/tex]
notice, the slopes are different, and you know what that means.
