Let's write each one in the form y = ax + b
1).12x-4y=8 → y = 3.x + 2
2).3y=-x+5 → y = (-1/3)x +5/3
3).y=1/3x-5 → y = (1/3)x -5
4).12x-10=4y → y = 3.x - 5/2
5).2/3×+2y=8 → y = (-1/3).x +4
1) and 4) are parallel since they have the same slope (m=3)
2) and 5) are parallel (m = -1/3 = same)
1) and 2) are perpendicular since the product of their slopes = -1 [(3).(-1/3)]
1) and 5) are perpendicular ((3).(-1/3) = -1
2) and 4) are perpendicular ((3).(-1/3) = -1
4) and 5) are perpendicular ((3).(-1/3) = -1
