Write the equation that is paralell to y-3x=6. We didn't learn this yet, would you start by putting it as y=3x+6?

Since the new line is parallel to the given line, it should differ only in the constant

So it would be y-3x = c

to find that constant, you must be given one more piece of information, such as a point lying on the new line.
sub in the values of the point to find c