The first equation is given in slope-intercept form but the second equation is not; so, let us convert the second equation to the slope-intercept form.
In the equation
[tex]5y-15x=18[/tex]
adding 15x to both sides gives
[tex]5y=15x+18[/tex]
and then dividing both sides by 5 gives
[tex]y=3x+\frac{18}{5}[/tex]
This equation has exactly the same equation as y = 3x + 5; therefore, the two lines are parallel.
