Tính.

\(\frac{1}{4}\) + \(\frac{1}{{16}}\) = \(\frac{4}{{16}}\) + \(\frac{1}{{16}}\) = \(\frac{5}{{16}}\)

\(\frac{{34}}{{45}}\) – \(\frac{1}{3}\) = \(\frac{{34}}{{45}}\) – \(\frac{{15}}{{45}}\) = \(\frac{{19}}{{45}}\)

\(\frac{8}{{35}}\) × \(\frac{7}{{64}}\) = \(\frac{1}{{40}}\)

\(\frac{5}{{18}}\) : \(\frac{{20}}{9}\) = \(\frac{5}{{18}}\) × \(\frac{9}{{20}}\) = \(\frac{1}{8}\)