Question 980768
{{{m=(0-(-4))/(-1-2)}}}
{{{m=-4/3}}}


Pick a point given, either; and plug m and point into point-slope form equation.
{{{y=-(4/3)(x+1)}}}, and a couple of steps were skipped, as done in the head without first writing formally into the form.


Now, continue to simplify, which would result in the slope-intercept form you wanted.