the slopes of perpendicular lines are negative reciprocal to each other
ex. the negative reciprocal to 5/2 is -2/5
once you find the perpendicular slope, you plug in the point and slope into the point-slope form of a line and then rearrange it into the slope-intercept form to get your answer
point slope
[tex]y-y_1 = m(x-x_1)[/tex]
slope intercept form
[tex]y=mx+b[/tex]