For y = mx+b, m is the slope and (0,b) is the y-intercept.
Two lines are parallel if they have the same slope, but have different y-intercepts.
So, if y = 5x+8, then y = 5x - 3 would be a line parallel to y = 5x + 8. Of course, any number other than -3 (except 8) would also work.
