Hi,
parallel (lines slant in same direction):Slopes identical
perpendicular: Slopes are negative reciprocals of one another
Neither: slopes do not satisfy either of the above:
4x+8y=16 OR y = (-1/2)x + 2 m = -1/2
3x+6y=7 OR y = (-1/2)x + 7/6 m = -1/2
These lines are Parallel, their slopes are identical