Answer:
None.
Step-by-step explanation:
To be parallel, slope must be equal
To be perpendicular, product of slope must be -1
For Slope of y=-x-
12
x+y=-12
Slope= - coefficient of x/coefficient of y = -1/1=-1
For Slope of -6x - 12y = 21
Slope= - coefficient of x/coefficient of y = -(-6)/-12=-1/2
They are neither same (-1,1/2) nor is their product -1(-1*-1/2=1/2)
Thus, they are neither parallel nor perpendicular.
