Giải thích các bước giải:
\[\begin{array}{l} a)\,4 - \dfrac{2}{3} - \dfrac{{10}}{{24}} = \dfrac{4}{1} - \dfrac{2}{3} - \dfrac{5}{{12}} = \dfrac{{48 - 8 - 5}}{{12}} = \dfrac{{35}}{{12}}\\ b)\,\,\dfrac{{12}}{7} \times \dfrac{3}{4} \times \dfrac{3}{{14}} = \dfrac{{3 \times 3 \times 3}}{{7 \times 14}} = \dfrac{{27}}{{98}}\\ c)\,\,2 + 21\dfrac{4}{{18}} = 23\dfrac{4}{{18}} = 23\dfrac{2}{9} \end{array}\]
Đáp số: `a,` `35/12`; `b,` `27/98`; `c,` `23``2/9`
