[tex]\bf \begin{array}{lllll}
&x_1&y_1&x_2&y_2\\
% (a,b)
&({{ 1}}\quad ,&{{ -1}})\quad
% (c,d)
&({{ 5}}\quad ,&{{ -7}})
\end{array}
\\\\\\
% slope = m
slope = {{ m}}= \cfrac{rise}{run} \implies
\cfrac{{{ y_2}}-{{ y_1}}}{{{ x_2}}-{{ x_1}}}\implies \cfrac{-7-(-1)}{5-1}\implies \cfrac{-7+1}{5-1}
\\\\\\
\cfrac{-6}{4}\implies -\cfrac{3}{2}[/tex]
