1: \(\dfrac{3}{7}+\left(-\dfrac{5}{2}\right)+\left(-\dfrac{3}{5}\right)\)
\(=\dfrac{3}{7}-\dfrac{5}{2}-\dfrac{3}{5}\)
\(=\dfrac{30}{70}-\dfrac{175}{70}-\dfrac{42}{70}\)
\(=-\dfrac{187}{70}\)
2: \(\left(-\dfrac{4}{3}\right)+\left(-\dfrac{2}{5}\right)+\left(-\dfrac{3}{2}\right)\)
\(=-\dfrac{40}{30}+\dfrac{-12}{30}+\dfrac{-45}{30}\)
\(=\dfrac{-40-12-45}{30}=\dfrac{-97}{30}\)
3: \(\dfrac{4}{5}-\left(-\dfrac{2}{7}\right)-\dfrac{7}{10}\)
\(=\dfrac{8}{10}-\dfrac{7}{10}+\dfrac{2}{7}\)
\(=\dfrac{1}{10}+\dfrac{2}{7}=\dfrac{7}{70}+\dfrac{20}{70}=\dfrac{27}{70}\)
4: \(\dfrac{2}{3}-\left[\left(-\dfrac{7}{4}\right)-\left(\dfrac{1}{2}+\dfrac{3}{8}\right)\right]\)
\(=\dfrac{2}{3}+\dfrac{7}{4}+\left(\dfrac{1}{2}+\dfrac{3}{8}\right)\)
\(=\dfrac{2}{3}+\dfrac{14}{8}+\dfrac{4}{8}+\dfrac{3}{8}\)
\(=\dfrac{2}{3}+\dfrac{21}{8}=\dfrac{16}{24}+\dfrac{63}{24}=\dfrac{79}{24}\)
\(1,\dfrac{3}{7}+\left(-\dfrac{5}{2}\right)+\left(-\dfrac{3}{5}\right)\)
\(=\dfrac{3}{7}-\dfrac{5}{2}-\dfrac{3}{5}\)
\(=\dfrac{30}{70}-\dfrac{175}{70}-\dfrac{42}{70}\)
\(=\dfrac{30-175-42}{70}\)
\(=\dfrac{-187}{70}\)
\(2,\left(-\dfrac{4}{3}\right)+\left(-\dfrac{2}{5}\right)+\left(-\dfrac{3}{2}\right)\)
\(=\dfrac{-4}{3}-\dfrac{2}{5}-\dfrac{3}{2}\)
\(=\dfrac{-40}{30}-\dfrac{12}{30}-\dfrac{45}{30}\)
\(=\dfrac{\left(-40\right)-12-45}{30}\)
\(=\dfrac{-97}{30}\)
\(3,\dfrac{4}{5}-\left(-\dfrac{2}{7}\right)-\dfrac{7}{10}\)
\(=\dfrac{4}{5}+\dfrac{2}{7}-\dfrac{7}{10}\)
\(=\left(\dfrac{4}{5}-\dfrac{7}{10}\right)+\dfrac{2}{7}\)
\(=\left(\dfrac{8}{10}-\dfrac{7}{10}\right)+\dfrac{2}{7}\)
\(=\dfrac{1}{10}+\dfrac{2}{7}\)
\(=\dfrac{7}{70}+\dfrac{20}{70}\)
\(=\dfrac{27}{70}\)
\(4,\dfrac{2}{3}-\left[\left(-\dfrac{7}{4}\right)-\left(\dfrac{1}{2}+\dfrac{3}{8}\right)\right]\)
\(=\dfrac{2}{3}+\left[\dfrac{7}{4}+\dfrac{1}{2}+\dfrac{3}{8}\right]\)
\(=\dfrac{2}{3}+\left[\dfrac{14}{8}+\dfrac{4}{8}+\dfrac{3}{8}\right]\)
\(=\dfrac{2}{3}+\dfrac{21}{8}\)
\(=\dfrac{16}{24}+\dfrac{63}{24}\)
\(=\dfrac{79}{24}\)
