Ответ:

а) \(\dfrac{a^2}{6}:\dfrac{a}{3}=\dfrac{a^2}{6}\cdot\dfrac{3}{a}=\dfrac{a}{2}\).

б) \(\dfrac{24}{b^2}\cdot\dfrac{b^3}{36}=\dfrac{2b}{3}\).

в) \(\dfrac{n^{24}}{28}:\dfrac{n^{39}}{56}=\dfrac{n^{24}}{28}\cdot\dfrac{56}{n^{39}}=\dfrac{2}{n^{15}}\).

г) \(\dfrac{m^5}{10}\cdot\dfrac{100}{m^{12}}=\dfrac{10}{m^7}\).