y = -1/3x + 5....slope here is -1/3. A perpendicular line will have a negative reciprocal slope. All that means is " flip " the slope and change the sign. So ur perpendicular line will have a slope of 3.
y = 3x....has a slope of 3, so this is perpendicular.
3x - y = 2.....y = 3x- 2.....has a slope of 3 and is therefore perpendicular
3x - y = 6.....y = 3x - 6...has a slope of 3 and is perpendicular