[tex]\bf (\stackrel{x_1}{1}~,~\stackrel{y_1}{2})\qquad(\stackrel{x_2}{5}~,~\stackrel{y_2}{4})\\\\\\ slope = m\implies\cfrac{\stackrel{rise}{ y_2- y_1}}{\stackrel{run}{ x_2- x_1}}\implies \cfrac{4-2}{5-1}\implies \cfrac{2}{4}\implies \cfrac{1}{2}[/tex]
