we have the lines
x-3=6
x=6+3
x=9
this is a vertical line (parallel to the y-axis)
The slope is undefined
and
y=3x+4
The slope is m=3
Compare their slopes
1) Their slopes are not equal -----> are not parallel lines
2) Their slopes are not negative reciprocal -----> are not perpendicular lines
therefore
The answer is neither