Answer:
If the slopes of two lines are the same then the line is parallel.
If the slope of one line is the negative inverse of the other line then it is perpendicular.
If the two lines intersect and they are not perpendicular they are neither (so if they do not follow the rules above then they are neither).
Step-by-step explanation:
If you have y=2x+3 and y=2x-3 then they are parallel because they have the same slope and they are not the same line.
If you have y=2x+3 and y= (-1/2)x - 3 then they are perpendicular because the slope of line two is the negative inverse of the first line.
If you don't get negative inverse:
If you have 2x then the inverse is 1/2x. Then the negative of (1/2)x is (-1/2)x
