assuming you meant the slope-intercept form of course,
[tex]\bf \begin{array}{ccccccccc}
&&x_1&&y_1&&x_2&&y_2\\
% (a,b)
&&(~ 3 &,& 4~)
% (c,d)
&&(~ 5 &,& 16~)
\end{array}
\\\\\\
% slope = m
slope = m\implies
\cfrac{\stackrel{rise}{ y_2- y_1}}{\stackrel{run}{ x_2- x_1}}\implies \cfrac{16-4}{5-3}\implies \cfrac{12}{2}\implies 6
\\\\\\
% point-slope intercept
\stackrel{\textit{point-slope form}}{y- y_1= m(x- x_1)}\implies y-4=6(x-3)
\\\\\\
y-4=6x-18\implies y=6x-14[/tex]
