Tính hợp lý:

\(A=\dfrac{7}{12}+\dfrac{5}{12}:6-\dfrac{11}{36}\)               \(B=\left(\dfrac{4}{5}+\dfrac{1}{2}\right):\left(\dfrac{3}{13}-\dfrac{8}{13}\right)\)

\(C=\left(\dfrac{2}{3}-\dfrac{1}{4}+\dfrac{5}{11}\right):\left(\dfrac{5}{12}+1-\dfrac{7}{11}\right)\)

Tính hợp lý:

\(a.\dfrac{-3}{5}+\dfrac{7}{21}+\dfrac{-4}{5}+\dfrac{7}{5}\)                 \(b.\dfrac{-3}{17}+\left(\dfrac{2}{3}+\dfrac{3}{17}\right)\)

\(c.\dfrac{-5}{21}+\left(\dfrac{-16}{21}+1\right)\)

Tính:

\(a.\dfrac{1}{5}+\dfrac{-3}{4}\)            \(b.\dfrac{1}{3}-\dfrac{1}{6}\)