First, write both lines in the same form. The second line can be written as: $$3x + 4y + \frac{15}{2} = 0$$ The distance between parallel lines $ax + by + c_1 = 0$ and $ax + by + c_2 = 0$ is: $$d = \frac{|c_1 - c_2|}{\sqrt{a^2 + b^2}}$$ Here: $a = 3$, $b = 4$, $c_1 = -5$, $c_2 = \frac{15}{2}$ $$d = \frac{\left|-5 - \frac{15}{2}\right|}{\sqrt{9 + 16}} = \frac{\left|\frac{-10 - 15}{2}\right|}{5} = \frac{\frac{25}{2}}{5} = \frac{25}{10} = \frac{5}{2}$$