[tex]\bf \begin{array}{ccccccccc}
&&x_1&&y_1&&x_2&&y_2\\
% (a,b)
&&(~ 6 &,& -2~)
% (c,d)
&&(~-3 &,& 7~)
\end{array}
\\\\\\
% slope = m
slope \implies
\cfrac{\stackrel{rise}{ y_2- y_1}}{\stackrel{run}{ x_2- x_1}}\implies \cfrac{7-(-2)}{-3-6}\implies \cfrac{7+2}{-3-6}\implies \cfrac{9}{-9}\implies -1[/tex]
