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

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