to get the equation of a straight line, all we need is two points on it... say hmmm this one has (0 , 6) and (6 , 2), so let's use those.
[tex]\bf (\stackrel{x_1}{0}~,~\stackrel{y_1}{6})\qquad (\stackrel{x_2}{6}~,~\stackrel{y_2}{2}) \\\\\\ slope = m\implies \cfrac{\stackrel{rise}{ y_2- y_1}}{\stackrel{run}{ x_2- x_1}}\implies \cfrac{2-6}{6-0}\implies \cfrac{-4}{6}\implies -\cfrac{2}{3} \\\\\\ \begin{array}{|c|ll} \cline{1-1} \textit{point-slope form}\\ \cline{1-1} \\ y-y_1=m(x-x_1) \\\\ \cline{1-1} \end{array}\implies y-6=-\cfrac{2}{3}(x-0) \\\\\\ y-6=-\cfrac{2}{3}x\implies y=-\cfrac{2}{3}x+6[/tex]
