Question

Which pair of lines are perpendicular to one another?

-3x+2y=10 and 3y=-2x+12
7x+4y=20 and y–3=-4/7
x=4y+4 and 4x+4y=4
2x+5y=45 and y+2/5x=-9

Answer 1

Perpendicular lines have slopes that are inverse (i.e. slope of 2, perpendicular slope is -1/2)

So although the x is missing for a part of the second pair, that seems to be the only answer that would make sense through process of elimination