Answer:
If there is not a typo and you aren't missing a minus sign on the slopes, l and m are simmetrical relative to the line
If there is a typo nad one of the slopes is negative, they're perpendicular.
Step-by-step explanation:
The product of the slope is 1 -unless you forgot a minus sign somewhere.
In general, two lines of the form are simmetrical relative to . Alas, the intercepts are different, but it's easy to spot by drawing them that they would be simmetrical to the parallel to passing through their intersection, by translation. Let's find that point
Their simmetry line - which is also their angular bisector! - is