[tex]\bf (\stackrel{x_1}{-4}~,~\stackrel{y_1}{-3})\qquad (\stackrel{x_2}{w}~,~\stackrel{y_2}{9}) \\\\\\ slope = m\implies \cfrac{\stackrel{rise}{ y_2- y_1}}{\stackrel{run}{ x_2- x_1}}\implies \cfrac{9-(-3)}{w-(-4)}=\stackrel{\stackrel{slope}{\downarrow }}{4}\implies \cfrac{9+3}{w+4}=4 \\\\\\ 12=4w+16\implies -4=4w\implies \cfrac{-4}{4}=w\implies -1=w[/tex]
