`1, [1/3(6/5 - 9/4) - 7/5(15/14 + 5/7)] : (1/2 - 1/3 + 5/6)`
`= [1/3 . (-21)/20 - 7/5 . 25/14] : (1/6 + 5/6)`
`= [-7/20-5/2] : 1`
`= -57/20 : 1`
`= -57/20`
`10, 21/10 : (12/5 - 9/10) . (-4/7) - 3/2(1/6 - 7/12) + 1/5(3/2 - 1/4)`
`= 21/10 : 3/2 . (-4/7) - 3/2 . (-5)/12 + 1/5 . 5/4`
`= 7/5 . (-4/7) + 5/8 + 1/4`
`= -4/5 + 5/8 + 1/4`
`= 3/40`
\(1,\left[\dfrac{1}{3}\left(\dfrac{6}{5}-\dfrac{9}{4}\right)-\dfrac{7}{5}\left(\dfrac{15}{14}+\dfrac{5}{7}\right)\right]:\left(\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{5}{6}\right)\)
\(=\left[\dfrac{1}{3}.\left(\dfrac{24}{20}-\dfrac{45}{20}\right)-\dfrac{7}{5}.\left(\dfrac{15}{14}+\dfrac{10}{14}\right)\right]:\left(\dfrac{3}{6}-\dfrac{2}{6}+\dfrac{5}{6}\right)\)
\(=\left[\dfrac{1}{3}.\dfrac{-21}{20}-\dfrac{7}{5}.\dfrac{25}{14}\right]:\dfrac{6}{6}\)
\(=\left[\dfrac{1.\left(-7\right)}{1.20}-\dfrac{1.5}{1.2}\right].1\)
\(=\left[\dfrac{-7}{20}-\dfrac{5}{2}\right].1\)
\(=\left[\dfrac{-7}{20}-\dfrac{50}{20}\right].1\)
\(=\dfrac{-57}{20}.1\)
\(=\dfrac{-57}{20}\)
\(10,\dfrac{21}{10}:\left(\dfrac{12}{5}-\dfrac{9}{10}\right).\left(\dfrac{-4}{7}\right)-\dfrac{3}{2}.\left(\dfrac{1}{6}-\dfrac{7}{12}\right)+\dfrac{1}{5}.\left(\dfrac{3}{2}-\dfrac{1}{4}\right)\)
\(=\dfrac{21}{10}:\left(\dfrac{24}{10}-\dfrac{9}{10}\right).\left(\dfrac{-4}{7}\right)-\dfrac{3}{2}.\left(\dfrac{2}{12}-\dfrac{7}{12}\right)+\dfrac{1}{5}.\left(\dfrac{6}{4}-\dfrac{1}{4}\right)\)
\(=\dfrac{21}{10}:\dfrac{15}{10}.\left(\dfrac{-4}{7}\right)-\dfrac{3}{2}.\left(\dfrac{-5}{12}\right)+\dfrac{1}{5}.\dfrac{5}{4}\)
\(=\dfrac{21}{10}.\dfrac{10}{15}.\left(\dfrac{-4}{7}\right)-\dfrac{1.\left(-5\right)}{2.4}+\dfrac{1.1}{1.4}\)
\(=\dfrac{1.1.\left(-4\right)}{1.5.1}+\dfrac{5}{8}+\dfrac{1}{4}\)
\(=\dfrac{-4}{5}+\dfrac{5}{8}+\dfrac{1}{4}\)
\(=\dfrac{-32}{40}+\dfrac{25}{40}+\dfrac{10}{40}\)
\(=\dfrac{3}{40}\)
