Question 120884
These equations are in the form y=mx+b, where m is the slope of the line.  Perpendicular lines have opposite reciprocal slopes.  So for example, 2 and -1/2 are slopes of perpendicular lines.  So are:
3 and -1/3
4 and -1/4
100 and -1/100
You should be able to pick the pair that fit with this pattern.
Good luck!