(i) $$\dfrac {6}{7} < \dfrac {8}{7}$$
Here, the denominators are same. Therefore, the fraction having the greater numerator will be greater.
(ii) $$\dfrac {5}{8} > \dfrac {3}{8}$$
Here, the denominators are same. Therefore, the fraction having the greater numerator will be greater.
(iii) $$\dfrac {6}{13} > \dfrac {6}{17}$$
Here, the numerators are same. Therefore, the fraction having the lesser denominator will be greater.
(iv) $$\dfrac {5}{22} > \dfrac {3}{22}$$
Here, the denominators are same. Therefore, the fraction having the greater numerator will be greater.
(v) $$\dfrac {9}{47} < \dfrac {9}{42}$$
Here, the numerators are same. Therefore, the fraction having the lesser denominator will be greater.