[tex]\bf (\stackrel{x_1}{2}~,~\stackrel{y_1}{5})\qquad(\stackrel{x_2}{-2}~,~\stackrel{y_2}{-5})\\\\\\ slope = m\implies\cfrac{\stackrel{rise}{ y_2- y_1}}{\stackrel{run}{ x_2- x_1}}\implies \cfrac{-5-5}{-2-2}\implies \cfrac{-10}{-4}\implies \cfrac{5}{2}\\\\[-0.35em]\rule{34em}{0.25pt}\\\\\stackrel{\textit{now, what Billy did was}}{\cfrac{\stackrel{run}{ x_1- x_2}}{\stackrel{rise}{ y_1- y_2}}}\implies \cfrac{2-(-2)}{5-(-5)}[/tex]
