a) \(x-\dfrac{2}{3}=\dfrac{-5}{12}.x=\dfrac{-5}{12}+\dfrac{2}{3}. x=\dfrac{-5}{12}+\dfrac{8}{12}.x=\dfrac{3}{12}.x=\dfrac{1}{4}\)

b) \(\dfrac{8}{5}:x=\dfrac{-2}{3}.x=\dfrac{8}{5}:\dfrac{-2}{3}=\dfrac{8}{5}\times\dfrac{3}{-2}=\dfrac{24}{-10}=\dfrac{-12}{5}\)

c) \(1-\dfrac{3}{7}\times x=-\dfrac{2}{7}.\dfrac{-3}{7}\times x=-\dfrac{2}{7}-\dfrac{7}{7}.\dfrac{-3}{7}\times x=-\dfrac{9}{7}.x=-\dfrac{9}{7}\times-\dfrac{7}{3}=3\)

a)\(\dfrac{-2}{7}+\dfrac{2}{7}:\dfrac{3}{5}=\dfrac{-2}{7}+\dfrac{2}{7}\times\dfrac{5}{3}=\dfrac{-2}{7}+\dfrac{10}{21}=\dfrac{-6}{21}+\dfrac{10}{21}=\dfrac{4}{21}\)

b)\(\dfrac{-8}{19}+\dfrac{-4}{21}-\dfrac{17}{21}+\dfrac{27}{19}=(\dfrac{-8}{19}+\dfrac{27}{19})+(\dfrac{-4}{21}-\dfrac{17}{21})=\dfrac{19}{19}+\dfrac{-21}{21}=1-1=0\)

c) \(\dfrac{6}{5}\times\dfrac{3}{13}-\dfrac{6}{5}\times\dfrac{16}{13}=\dfrac{6}{5}\times(\dfrac{3}{13}-\dfrac{16}{13})=\dfrac{6}{5}\times\dfrac{-13}{13}=\dfrac{-6}{5}\)