#Bẻox_Rebecca
`text{Đáp án:}`
a, $\dfrac{-1}{39}$+$\dfrac{-1}{52}$
=$\dfrac{-7}{156}$
b, $\dfrac{-6}{9}$+$\dfrac{-12}{16}$
=$\dfrac{-17}{12}$
c,$\dfrac{-2}{5}$-$\dfrac{3}{11}$
=$\dfrac{-37}{55}$
d,$\dfrac{-34}{37}$.$\dfrac{74}{-85}$
=$\dfrac{4}{5}$
e, $\dfrac{-5}{9}$:$\dfrac{-7}{18}$
=$\dfrac{10}{7}$
f, $\dfrac{3}{7}$+($\dfrac{-5}{2}$)+($\dfrac{-3}{5}$)
=$\dfrac{-29}{41}$+$\dfrac{-3}{5}$
=$\dfrac{-187}{70}$
g, $\dfrac{4}{5}$-($\dfrac{-2}{7}$)-($\dfrac{7}{10}$)
=$\dfrac{38}{25}$-$\dfrac{7}{10}$
=$\dfrac{27}{70}$