Decide wheather the pair of lines is parrall, perpendicular or neither.

what is the slope?
5x+4y=6
4x-5y=10

I GOT -5/4 AND 4/5 NEITHER.

isn't the product of their slopes = -1 ??

or notice that one slope is the negative reciprocal of the other, so....

the lines are perpendicular.