\(c,\dfrac{-5}{21}.\dfrac{7}{10}+\dfrac{5}{9}=\dfrac{-35}{210}+\dfrac{5}{9}=\dfrac{7}{18}\)
\(b,\dfrac{5}{-6}+\dfrac{-3}{-4}-\dfrac{11}{8}=-\dfrac{5}{6}+\dfrac{3}{4}-\dfrac{11}{8}=-\dfrac{20}{24}+\dfrac{18}{24}-\dfrac{33}{24}=\dfrac{-20+18-33}{24}=-\dfrac{35}{24}\)
\(d,\dfrac{8}{7}.\dfrac{2}{9}+\dfrac{8}{9}.\dfrac{4}{7}+\dfrac{8}{7}.\dfrac{15}{9}=\dfrac{16}{63}+\dfrac{32}{63}+\dfrac{120}{63}=\dfrac{16+32+120}{63}=\dfrac{168}{63}=\dfrac{8}{3}\)
Đúng 3
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