a: \(\left(-\frac25\right)\cdot\frac{4}{15}+\left(-\frac{3}{10}\right)\cdot\frac{4}{15}\)
\(=\frac{4}{15}\left(-\frac25-\frac{3}{10}\right)\)
\(=\frac{4}{15}\cdot\frac{-7}{10}=\frac{-28}{150}=-\frac{14}{75}\)
b: \(\left(-\frac37\right)\cdot\frac{5}{11}+\left(-\frac{5}{14}\right)\cdot\frac{5}{11}\)
\(=\frac{5}{11}\left(-\frac37-\frac{5}{14}\right)\)
\(=\frac{5}{11}\cdot\frac{-11}{14}=-\frac{5}{14}\)
c: \(\left(-\frac56+\frac25\right):\frac38+\left(\frac45-\frac{11}{30}\right):\frac38\)
\(=\left(-\frac56+\frac25+\frac45-\frac{11}{30}\right):\frac38\)
\(=\left(-\frac{25}{30}+\frac{36}{25}-\frac{11}{30}\right):\frac38=0\)
d: \(\left(-\frac34+\frac25\right):\frac37+\left(\frac35+\frac{-1}{4}\right):\frac37\)
\(=\left(-\frac34+\frac25+\frac35-\frac14\right):\frac37\)
=0
