tis noteworthy that perpendicular lines have negative reciprocal slopes, so if one say have a slope of a/b, the other has a slope of -b/a, so that, if we multiply both (a/b) * (-b/a) we get -1 as their product, that said, let's take a peek of the slopes of "n" and "m".
![\bf A(\stackrel{x_1}{-2}~,~\stackrel{y_1}{6})\qquad B(\stackrel{x_2}{4}~,~\stackrel{y_2}{8}) \\\\\\ \stackrel{slope}{m}\implies \cfrac{\stackrel{rise} {\stackrel{y_2}{8}-\stackrel{y1}{6}}}{\underset{run} {\underset{x_2}{4}-\underset{x_1}{(-2)}}}\implies \cfrac{2}{4+2}\implies \cfrac{2}{6}\implies \boxed{\cfrac{1}{3}} \\\\[-0.35em] ~\dotfill](https://img.qammunity.org/2020/formulas/mathematics/middle-school/iogf6alrcdlv47pn98sa65p06jnp64466p.png)

and well, since we know they're perpendicular
