a: \(=\dfrac{11}{4}\cdot\dfrac{-2}{5}+\dfrac{36}{5}\cdot\dfrac{11}{9}=\dfrac{11}{9}\cdot\dfrac{34}{5}=\dfrac{374}{45}\)
b: \(=3\cdot\left(\dfrac{5}{6}-\dfrac{25}{12}\right):\dfrac{30}{7}-\dfrac{1}{4}\cdot\dfrac{-2}{3}\)
\(=3\cdot\dfrac{7}{30}\cdot\dfrac{-15}{12}+\dfrac{1}{6}\)
\(=\dfrac{7}{10}\cdot\dfrac{-5}{4}+\dfrac{1}{6}\)
\(=\dfrac{-7}{8}+\dfrac{1}{6}=\dfrac{-21+4}{24}=\dfrac{-17}{24}\)