so now for this first one you have $\frac{ \sqrt{18} }{ 3\sqrt{36} }$ You know √18 is just √9*√2 and you know √9 is 3.....so the top is 3√2 you also know √36 is just √9*√4 and you know √9 =3 and √4 = 2 so the bottom leaves 3(3)(2) = 18 so you have 3√2 ------ 18 simplified gives √2 --- 6