\(\dfrac{7}{21}+\dfrac{-9}{36}\)

\(\dfrac{-12}{18}+\dfrac{-21}{35}\)

\(\dfrac{-18}{24}+\dfrac{15}{-21}\)

\(\dfrac{3}{21}+\dfrac{-6}{42}\)

\(\dfrac{-3}{5}+\dfrac{-4}{3}\)

\(2+\dfrac{-5}{4} \)

\(\dfrac{-2}{13}+\dfrac{-11}{26}\)

\(\dfrac{2}{5}+\dfrac{-1}{3}\)

\(\dfrac{3}{4}+\dfrac{-2}{7}\)

\(\dfrac{-3}{5}+\dfrac{-1}{3}\)