[tex]16.\\\\\dfrac{2}{3}+\dfrac{5}{6}-\dfrac{3}{10}=\dfrac{2\cdot10}{3\cdot10}+\dfrac{5\cdot5}{6\cdot5}-\dfrac{3\cdot3}{10\cdot3}=\dfrac{20}{30}+\dfrac{25}{30}-\dfrac{9}{30}\\\\=\dfrac{20+25-9}{30}=\dfrac{36}{30}=\dfrac{36:6}{30:6}=\dfrac{6}{5}=\boxed{1\frac{1}{5}}[/tex]
[tex]17.\\\\\dfrac{24}{7}:\dfrac{14}{21}=\dfrac{24}{7}:\dfrac{14:7}{21:7}=\dfrac{24}{7}:\dfrac{2}{3}=\dfrac{24}{7}\cdot\dfrac{3}{2}=\dfrac{72}{14}=\dfrac{72:2}{14:2}\\\\=\dfrac{36}{7}=\boxed{5\frac{1}{7}}[/tex]
