\(1,\left(\dfrac{-2}{3}+\dfrac{3}{7}\right):\dfrac{4}{5}+\left(\dfrac{-1}{3}+\dfrac{4}{7}\right):\dfrac{4}{5}\)
\(=\left(\dfrac{-14}{21}+\dfrac{9}{21}\right).\dfrac{5}{4}+\left(\dfrac{-7}{21}+\dfrac{12}{21}\right).\dfrac{5}{4}\)
\(=\dfrac{-5}{21}.\dfrac{5}{4}+\dfrac{5}{21}.\dfrac{5}{4}\)
\(=\dfrac{5}{4}.\left(\dfrac{-5}{21}+\dfrac{5}{21}\right)\)
\(=\dfrac{5}{4}.0\)
\(=0\)
\(2,\dfrac{5}{9}:\left(\dfrac{1}{11}-\dfrac{5}{22}\right)+\dfrac{5}{9}:\left(\dfrac{1}{15}-\dfrac{2}{3}\right)\)
\(=\dfrac{5}{9}:\left(\dfrac{2}{22}-\dfrac{5}{22}\right)+\dfrac{5}{9}:\left(\dfrac{1}{15}-\dfrac{10}{15}\right)\)
\(=\dfrac{5}{9}:\dfrac{-3}{22}+\dfrac{5}{9}:\dfrac{-9}{15}\)
\(=\dfrac{5}{9}.\dfrac{-22}{3}+\dfrac{5}{9}:\dfrac{-3}{5}\)
\(=\dfrac{5}{9}.\dfrac{-22}{3}+\dfrac{5}{9}.\dfrac{-5}{3}\)
\(=\dfrac{5}{9}.\left(\dfrac{-22}{3}+\dfrac{-5}{3}\right)\)
\(=\dfrac{5}{9}.\dfrac{-27}{3}\)
\(=\dfrac{5}{9}.\left(-9\right)\)
\(=-5\)
\(3,\left(1\dfrac{3}{7}-\dfrac{5}{12}\right):\dfrac{4}{5}-\left(\dfrac{3}{7}-\dfrac{17}{12}\right):\dfrac{4}{5}\)
\(=\left(\dfrac{10}{7}-\dfrac{5}{12}\right).\dfrac{5}{4}-\left(\dfrac{36}{84}-\dfrac{119}{84}\right).\dfrac{5}{4}\)
\(=\left(\dfrac{120}{84}-\dfrac{35}{84}\right).\dfrac{5}{4}-\dfrac{-83}{84}.\dfrac{5}{4}\)
\(=\dfrac{85}{84}.\dfrac{5}{4}-\dfrac{-83}{84}.\dfrac{5}{4}\)
\(=\dfrac{5}{4}.\left(\dfrac{85}{84}-\dfrac{-83}{84}\right)\)
\(=\dfrac{5}{4}.\dfrac{168}{84}\)
\(=\dfrac{5}{4}.2\)
\(=\dfrac{5}{2}\)
\(4,\dfrac{29}{19}.\dfrac{49}{51}+\dfrac{29}{19}.\dfrac{34}{51}-\dfrac{29}{19}.\dfrac{32}{51}\)
\(=\dfrac{29}{19}.\left(\dfrac{49}{51}+\dfrac{34}{51}-\dfrac{32}{51}\right)\)
\(=\dfrac{29}{19}.\dfrac{51}{51}\)
\(=\dfrac{29}{19}.1\)
\(=\dfrac{29}{19}\)
