\(C=\dfrac{2}{5}+\dfrac{1}{5}.\left(-\dfrac{3}{4}\right)\)
\(C=\dfrac{2}{5}+\left(-\dfrac{3}{20}\right)\)
\(C=\dfrac{1}{4}\)
\(E=2:\left(\dfrac{1}{2}-\dfrac{2}{3}\right)^3\)
\(E=2:\left(-\dfrac{1}{6}\right)^3\)
\(E=2:\left(-\dfrac{1}{216}\right)\)
\(E=-432\)