Réponse:

[tex] \frac{8}{5} \times \frac{5}{7} = \frac{8 \times 5}{5 \times 7} = \frac{8}{7} \\ b = \frac{ - 3}{ 10} \times \frac{ - 11}{3} = \frac{ - 3 \times ( - 11)}{10 \times 3} = \frac{3 \times 1}{10 \times 3} = \frac{11}{10} \\ [/tex]