[tex]\bf 3y+x=9\implies 3y=-x+9\implies y=\cfrac{-x+9}{3}\implies y=\cfrac{-x}{3}+\cfrac{9}{3} \\\\\\ y=\stackrel{\stackrel{m}{~\hfill \downarrow }}{-\cfrac{1}{3}} x+3\qquad \impliedby \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}[/tex]
