[tex]\bf \begin{array}{ccccccccc}
&&x_1&&y_1&&x_2&&y_2\\
% (a,b)
&&(~ 4 &,& 3~)
% (c,d)
&&(~ -4 &,& -1~)
\end{array}
\\\\\\
% slope = m
slope = m\implies
\cfrac{\stackrel{rise}{ y_2- y_1}}{\stackrel{run}{ x_2- x_1}}\implies \cfrac{-1-3}{-4-4}\implies \cfrac{-4}{-8}\implies \cfrac{1}{2}
\\\\\\
% point-slope intercept
\stackrel{\textit{point-slope form}}{y- y_1= m(x- x_1)}\implies y-3=\cfrac{1}{2}(x-4)
\\\\\\
y-3=\cfrac{1}{2}x-2\implies y=\cfrac{1}{2}x+1[/tex]
