Question 180540
You can solve this problem by solving the equations, and takinf them to the slope-intercept form and compare their slopes.

if you solve -3x-18y = 6 for Y, then you get m = (-1/6)

(a). y = (-1/6)x-(1/3) 

if you solve 6x-y = 14 for Y, then you get m = (6)

(b). y = (6)x - 14

The relationship between both slopes is that if you multiply them, then you will get -1.
This tells you that the lines are perpendicular.