Tính bằng cách thuận tiện

a) \(\frac{5}{{24}} + \frac{7}{{24}} + \frac{{15}}{{24}}\)

\( = \frac{{5 + 7 + 15}}{{24}}\)

\[ = \frac{{27}}{{24}}\]

\[ = \frac{{27:3}}{{24:3}} = \frac{9}{8}\]

b) \(\frac{{13}}{{60}} + \frac{{19}}{{30}} + \frac{{11}}{{60}}\)

\[ = \left( {\frac{{13}}{{60}} + \frac{{11}}{{60}}} \right) + \frac{{19}}{{30}}\]

\[ = \frac{{24}}{{60}} + \frac{{19}}{{30}}\]

\[ = \frac{{24:2}}{{60:2}} + \frac{{19}}{{30}}\]

\[ = \frac{{12}}{{30}} + \frac{{19}}{{30}} = \frac{{31}}{{30}}\]