Is y=-3x-8 perpendicular, parallel, or neither?

Y=-3x+8 is not parallel nor perpendicular to y=3x+8.

Thus, it is neither.

If one line is parallel to another line, then they will both have the same slope (the coefficient next to the x).

For instance, y=5x+8 is parallel to y=5x-4.

If one line is perpendicular to another line, then the slopes must be negative reciprocals of one another (reciprocals multiply together and yield one, like 1/3 and 3.)

A parallel line to y=-3x-8 would be y=-3x

A perpendicular line to y=-3x-8 would be y=1/3x

Since the line we are comparing y=-3x-8 to, which is y=3x+8, meets neither of the constraints for being parallel or perpendicular, the correct answer is neither.