The two lines are parallel if they have the same gradient, so for a line in the form y=mx+c, m of the two lines must be the same.Line 1 is already in this form so we need to rearrange line 2 to be in this form.3y-9x+5=0. First rearrange to have y on the left hand side. -5 and +9x.3y=9x-5. Then divide by 3.y=3x-5/3. Line 1 and line 2 both have 3 as their gradients, so are parallel.