Bonjour pourriez-vous m’aider svp ex4, merci

[tex] Bonjour; \\\\\\ A=\dfrac{2}{3}:\dfrac{5}{4} = \dfrac{2}{3}\times\dfrac{4}{5} = \dfrac{2\times4}{3\times5} =\dfrac{8}{15}\ . [/tex]

[tex] B=\dfrac{15}{-3}:\dfrac{-2}{5} =\dfrac{5\times3}{-3}:\dfrac{-2}{5} =\dfrac{5}{-1}:\dfrac{-2}{5} =\dfrac{5}{-1}\times\dfrac{5}{-2} \\\\\\ =\dfrac{5\times5}{(-1)\times(-2)}= \dfrac{25}{2} \ . [/tex]

[tex] C =\dfrac{-11}{15} : \dfrac{22}{10} = - \dfrac{11}{15} : \dfrac{22}{10}   = - \dfrac{11}{3\times5} : \dfrac{2\times11}{2\times5}   \\\\\\ = - \dfrac{11}{3\times5} : \dfrac{11}{5}   = - \dfrac{11}{3\times5} \times \dfrac{5}{11}   = - \dfrac{11\times5}{3\times5\times11} = - \dfrac{1}{3}\ .  [/tex]