\(\frac{-1}{39}+\frac{-1}{52}=\frac{-7}{156}\)
\(\frac{-6}{9}+\frac{12}{16}=\frac{-2}{3}+\frac{3}{4}=\frac{1}{12}\)
\(\frac{-2}{5}-\frac{-3}{11}-\frac{34}{37}-\frac{74}{-85}=\frac{-1215}{6919}\)
\(\frac{-5}{9}:\frac{-7}{18}=\frac{-5}{9}.\frac{-18}{7}=\frac{10}{7}\)