Determine whether each pair of lines is parallel, perpendicular, or neither.

There is no question.
For lines are parallel, graphs : they must have same gradients as every points. Geometry: prove using alternate angles, corresponding angles or interior angles
For lines are perpendicular, graphs: their gradients multiply to give -1. Geometry: they form a right angle

Iam unsure about what the proof is, therefore as much as wish to i can not.