[tex](\stackrel{x_1}{-1}~,~\stackrel{y_1}{4})\qquad(\stackrel{x_2}{4}~,~\stackrel{y_2}{-1})\\\\\\% slope = m\stackrel{slope}{m}\implies\cfrac{\stackrel{rise}{\stackrel{y_2}{-1}-\stackrel{y1}{4}}}{\underset{run}{\underset{x_2}{4}-\underset{x_1}{(-1)}}}\implies \cfrac{-5}{4+1}\implies \cfrac{-5}{5}\implies -1[/tex]
[tex]\begin{array}{|c|ll}\cline{1-1}\textit{point-slope form}\\\cline{1-1}\\y-y_1=m(x-x_1)\\\\\cline{1-1}\end{array}\implies y-\stackrel{y_1}{4}=\stackrel{m}{-1}[x-\stackrel{x_1}{(-1)}]\\\\\\y-4=-1(x+1)\implies y-4=-x-1\implies \blacktriangleright y = -x+3 \blacktriangleleft[/tex]