LOL...
y=mx+b is your standard equation.
The slope of your equation is 5x, and since they're parallel, they will have the same slope.
Now, plug in your x and y coordinates. The origin is at (0,0) so follow (x,y).
0=5(0)+b and then solve for b.
0=0+b
0=b
Since b=0, you can leave it out. Your final equation would be y=5x.
I did far too much work for that. /complicates things