Ta có: \(23\dfrac{1}{4}:\left(-\dfrac{3}{7}\right)-23\dfrac{1}{4}:\left(-\dfrac{5}{7}\right)\)
\(=\dfrac{93}{4}\cdot\dfrac{-7}{3}-\dfrac{93}{4}\cdot\dfrac{-7}{5}\)
\(=\dfrac{93}{4}\cdot\left(-\dfrac{7}{3}+\dfrac{7}{5}\right)\)
\(=\dfrac{93}{4}\cdot\dfrac{-14}{15}=-\dfrac{217}{10}\)