Given:
A: 3x + y = 6
B: 6x - 2y = 4
C: y = 3x - 2
D: y = 1/3 x + 7
To figure out which two lines are perpendicular, we must look at the slopes of each one after putting them into standard form, y = mx + b.
Standard Form:
A: y = -3x + 6
B: y = 3x - 2
C: y = 3x - 2
D: y = (1/3)x + 7
Lines are perpendicular when their slopes are opposite inverses of eachother.
The opposite of -3 is 3 and the inverse of 3 is 1/3.
Therefore, lines A and D are perpendicular to one another :)