a: =-5/21
b: \(=\dfrac{15}{4}-\dfrac{9}{4}=\dfrac{6}{4}=\dfrac{3}{2}\)
c: \(=\left(\dfrac{31}{10}-\dfrac{25}{10}\right)\cdot3-2=\dfrac{6}{10}\cdot3-2=\dfrac{18}{10}-\dfrac{20}{10}=\dfrac{-2}{10}=\dfrac{-1}{5}\)
d: \(=\dfrac{4}{3}\cdot\dfrac{1}{20}=\dfrac{4}{60}=\dfrac{1}{15}\)
a: \(=\dfrac{-15}{25}\cdot\dfrac{8}{16}=\dfrac{-3}{5}\cdot\dfrac{1}{2}=\dfrac{-3}{10}\)
b: \(=\dfrac{2}{3}+\dfrac{2}{7}=\dfrac{20}{21}\)
c: \(=\dfrac{3}{2}\cdot\dfrac{-3+2}{4}=\dfrac{3}{2}\cdot\dfrac{-1}{4}=\dfrac{-3}{8}\)
d: \(=\dfrac{7}{11}\cdot\dfrac{11}{7}\cdot\dfrac{-3}{41}=-\dfrac{3}{41}\)