okay, let's start with making it into y=mx+b (it's easier)
so right now it's 3x-y= -5
so we move 3x to the other side, which will make it -y=-3x-5.
The y cannot be negative, so we move the x as one to the other side, which will change the signs. Now it's y=3x-5.
Well, we know parallel means that it just has a different y-intercept. So, what I would always do (my best bet TBH, but someone knows a quicker way to figure it out, help us), is to find the y-intercept with the degree (-1,0)
the y-intercept means that that the x is at 0° and it touches line y. so, if we go up 3 and right once (positive slope), it would make the y-intercept 3, meaning the parallel line is y=3x+3.