[tex]\bf \begin{array}{ccccccccc}
&&x_1&&y_1&&x_2&&y_2\\
% (a,b)
&&(~{{ -2}} &,&{{ -1}}~)
% (c,d)
&&(~{{ -4}} &,&{{ -7}}~)
\end{array}
\\\\\\
% slope = m
slope = {{ m}}\implies
\cfrac{\stackrel{rise}{{{ y_2}}-{{ y_1}}}}{\stackrel{run}{{{ x_2}}-{{ x_1}}}}\implies \cfrac{-7-(-1)}{-4-(-2)}\implies \cfrac{-7+1}{-4+2}
\\\\\\
\cfrac{-6}{-2}\implies 3[/tex]
