\[ \begin{align*} \dfrac{16}{24} \times \dfrac{9}{8} \times \dfrac{5}{6} &= \dfrac{16\times 9\times 5}{24\times 8\times 6} \\ &= \dfrac{720}{1152} \\ &= \dfrac{5}{8} \end{align*} \] \[ \begin{align*} 3 \times \dfrac{5}{12} \times \dfrac{18}{25} &= \dfrac{3\times 5\times 18}{1\times 12\times 25} \\ &= \dfrac{270}{300} \\ &= \dfrac{9}{10} \end{align*} \] \[ \begin{align*} \dfrac{7}{10} \times \dfrac{20}{14} \times \dfrac{21}{6} &= \dfrac{7\times 20\times 21}{10\times 14\times 6} \\ &= \dfrac{2940}{840} \\ &= \dfrac{7}{2} \end{align*} \] \[ \begin{align*} \dfrac{4}{9} \times 27 \times \dfrac{3}{8} &= \dfrac{4\times 27\times 3}{9\times 1\times 8} \\ &= \dfrac{324}{72} \\ &= \dfrac{9}{2} \end{align*} \]