Is each line parallel, perpendicular, or neither parallel nor perpendicular to the line −x+4y=20?
y=−4x−3
y=−14x+6
−x+4y=8
4x+y=−1

Find the slopes of each
for
ax+by=c
slope=-a/b

for y=mx+b
m=slope

the slopes of paralell lines are equal
the slopes of perpendicular lines, when multiplied together, yeild -1

so
-1x+4y=20
sloope=-(-1)/4=1/4

check each

y=-4x-3
-4 times 1/4=-1
perpendicular

y=-1/4x+6
-1/4 and 1/4
neither

-1x+4y=8
-(-1)/4=1/4
1/4=1/4
paralell

4x+1y=-1
-4/1=-4
-4 times 1/4=-1
perpendicular

y=−4x−3: perpendicular
y=−14x+6: neither
−x+4y=8: paralell
4x+y=−1: perpendicular

It is the top one. the answer is -7. that is smallest