a:\(\dfrac{31}{17}+\dfrac{-5}{13}+\dfrac{-8}{13}-\dfrac{14}{17}\)
\(=\left(\dfrac{31}{17}-\dfrac{14}{17}\right)+\left(-\dfrac{5}{13}-\dfrac{8}{13}\right)\)
\(=\dfrac{17}{17}-\dfrac{13}{13}=1-1=0\)
b: \(\dfrac{-11}{12}\cdot\dfrac{18}{25}+\dfrac{-11}{12}\cdot\dfrac{7}{25}+\dfrac{5}{12}\)
\(=-\dfrac{11}{12}\left(\dfrac{18}{25}+\dfrac{7}{25}\right)+\dfrac{5}{12}\)
\(=-\dfrac{11}{12}+\dfrac{5}{12}=-\dfrac{6}{12}=-\dfrac{1}{2}\)
c: \(\left(\dfrac{5}{7}\cdot0,6-5:3\dfrac{1}{2}\right)\left(40\%-1.4\right)\cdot\left(-2\right)^3\)
\(=\left(\dfrac{5}{7}\cdot\dfrac{3}{5}-5:\dfrac{7}{2}\right)\left(-1\right)\cdot\left(-8\right)\)
\(=\left(\dfrac{3}{7}-\dfrac{10}{7}\right)\cdot8=-1\cdot8=-8\)