Question

What is the slope of a line perpendicular to the line 5x - 15y = 20?

A.) -10

B.) -3

C.) -1/3

D.) 3

Answer 1

5x-15y=20
5x-15y-20=0
slope=-5/-15
=1/3
if they are perpendicular
the other slope
=1/3×-1
=-1/3
the answer is c

Answer 2

Lets get started :)

5x - 15y = 20
Rearrange in order to make y the subject
15y = 5x - 20

Divide by 15 by the whole to isolate y
$\frac{15y=5x-20}{15}$
y = $\frac{1}{3}x$ - $\frac{4}{3}$

The slope of this equation is $\frac{1}{3}$

The slope of the perpendicular will be negative reciprocal = -3

Your answer is option B = -3