equation of y=1/3x -4; (-6, -3)
Not sure what you are asking, but the point (x = -6, y = -3) doesn't lie on the line y = (1/3)x - 4.
If you put x = -6 in this you get y = (1/3)*(-6) - 4 = -2 - 4 = -6 (not -3).