16. \(\left(-\frac{5}{9}+\frac{11}{36}\right)-\frac{7}{20}\)

\(-\frac{5}{9}+\frac{11}{36}=-\frac{20}{36}+\frac{11}{36}=-\frac{1}{4}\).

\(-\frac{1}{4}-\frac{7}{20}=-\frac{5}{20}-\frac{7}{20}=-\frac{3}{5}\).

Ответ: \(-\frac{3}{5}\).