m: \(\left(-\dfrac{1}{2}\right)-\left(-\dfrac{3}{5}\right)+\left(-\dfrac{1}{9}\right)+\dfrac{1}{71}-\left(-\dfrac{2}{7}\right)+\dfrac{4}{35}-\dfrac{7}{18}\)
\(=-\dfrac{1}{2}+\dfrac{3}{5}-\dfrac{1}{9}+\dfrac{1}{71}+\dfrac{2}{7}+\dfrac{4}{35}-\dfrac{7}{18}\)
\(=\left(\dfrac{3}{5}+\dfrac{2}{7}+\dfrac{4}{35}\right)+\left(-\dfrac{1}{2}-\dfrac{1}{9}-\dfrac{7}{18}\right)+\dfrac{1}{71}\)
\(=\dfrac{21+10+4}{35}+\dfrac{-9-2-7}{18}+\dfrac{1}{71}\)
\(=\dfrac{35}{35}+\dfrac{-18}{18}+\dfrac{1}{71}=\dfrac{1}{71}\)
n: \(\left(5+\dfrac{1}{5}-\dfrac{2}{9}\right)-\left(2-\dfrac{1}{23}-2\dfrac{3}{35}+\dfrac{5}{6}\right)-\left(8+\dfrac{2}{7}-\dfrac{1}{18}\right)\)
\(=5+\dfrac{1}{5}-\dfrac{2}{9}-2+\dfrac{1}{23}+\dfrac{73}{35}-\dfrac{5}{6}-8-\dfrac{2}{7}+\dfrac{1}{18}\)
\(=\left(5-2-8\right)+\left(\dfrac{1}{5}-\dfrac{2}{7}+\dfrac{73}{35}\right)+\left(-\dfrac{2}{9}-\dfrac{5}{6}+\dfrac{1}{18}\right)+\dfrac{1}{23}\)
\(=\left(-5\right)+\dfrac{7-10+73}{35}+\dfrac{-4-15+1}{18}+\dfrac{1}{23}\)
\(=-5+2-1+\dfrac{1}{23}=-5+\dfrac{1}{23}=\dfrac{-114}{23}\)
o: \(\dfrac{-5}{7}-\left(-\dfrac{5}{67}\right)+\dfrac{13}{30}+\dfrac{1}{2}+\left(-1\dfrac{5}{6}\right)+1\dfrac{3}{14}-\left(-\dfrac{2}{5}\right)\)
\(=\dfrac{-5}{7}+\dfrac{5}{67}+\dfrac{13}{30}+\dfrac{1}{2}-\dfrac{11}{6}+\dfrac{17}{14}+\dfrac{2}{5}\)
\(=\left(-\dfrac{5}{7}+\dfrac{1}{2}+\dfrac{17}{14}\right)+\left(\dfrac{13}{30}-\dfrac{11}{6}+\dfrac{2}{5}\right)+\dfrac{5}{67}\)
\(=\dfrac{-10+7+17}{14}+\dfrac{13-55+12}{30}+\dfrac{5}{67}\)
\(=\dfrac{14}{14}+\dfrac{-30}{30}+\dfrac{5}{67}=\dfrac{5}{67}\)