thực hiện phép tính
a. \(\dfrac{11}{21}+\dfrac{-2}{7}+\dfrac{10}{21}+\left(-1\dfrac{1}{5}\right)+\dfrac{-5}{7}\)
\(b.\left(0.25\right)^5.\left(-5\dfrac{5}{9}\right).\left(-4\right)^5\)
\(c.\dfrac{3}{22}.19\dfrac{1}{7}+\dfrac{3}{22}.2\dfrac{6}{7}-\sqrt{36}\)