---Lines that are parallel to each other will have the same slope
---Lines that are perpendicular to each other will have opposite reciprocal slopes
A line parallel to y = 1/3x + 2 --- C
x = 3y + 21
3y = x - 21
y = 1/3x - 7
A line perpendicular to x = 3 --- A
This is a vertical line, with an undefined slope. A perpendicular line will have a 0 slope.
A line perpendicular to 9x - 3y = 18 --- B
9x - 3y = 18
-3y = -9x + 18
y = 3x - 6
The opposite reciprocal of 3 is -1/3.
A line parallel to -4x + 8y = 9 --- D
-4x + 8y = 9
8y = 4x + 9
y = 1/2x + 9/8
A line that is parallel will have the same slope (1/2).
x - 2y = -2
-2y = -x - 2
y = 1/2x + 1
Hope this helps!