You can put this solution on YOUR website! In order for two lines be parallel, they must have the same slope.
If we convert all equations to this pattern: y=mx+b, m would be our slope.
So, let's compare them:
y=x+13 ... its slope is 1
2y=6x-3
y=3x-(3/2) ... its slope is 3
Since the slopes are different, we know they are not parallel.
Below is how the lines would look like in the cartesian plane.
The red line represents
The green line represents