Answer:
y = x/3 +2
Which can also be written as
y = (1/3)x +2
Explanation:
Now from the way your question is worded, I'll assume you mean 3y -x = -12, but do correct me.
3y -x = -12
3y = x -12
y = x/3 -12
So the gradient of this line is 1/3 and the y intercept is (0,-12).
We want a line parallel (with the same gradient) but a different y intercept.
If the line passes through (6,4) than the equasion of the line is equal when x = 6 and y = 4.
4 = 6/3 +c (c being the new y intercept for this parallel line)
4 = 2 +c
2 = c
Lets take that y intercept and put it back in our original equasion:
y = x/3 +2
And there's your answer :D