Ответ:

\(\frac{1}{24}+\frac{1}{36}=\frac{3+2}{72}=\frac{5}{72}\).

\(\frac{5}{72}:\frac{20}{7}=\frac{5}{72}\cdot\frac{7}{20}=\frac{7}{288}\).

Ответ: \(\frac{7}{288}\).