It is parallel to any line with the same slope. You must get the equation into slope intercept form by isolating the y.
3y=6x-9 Add 6x and subtract 9 to move them to the other side.
Y=2x-3 Divide by 3 to get y by itself.
Y=mx+b where the m is slope. Therefore, the slope is 2. Any line with a slope of 2 is parallel.