Réponse:
[tex] \frac{ - 7}{4} \div \frac{4}{9} = \frac{ - 7}{4} \times \frac{9}{4} [/tex]
donc c
[tex]a = \frac{1}{5} \times \frac{1}{5} = \frac{1}{25} \\ b = \frac{2}{3} \times 3 = \frac{6}{3} = 2 \\ c = \frac{3}{ - 7} \times \frac{ - 7}{1} = 3 \\ d = \frac{ - 8 \times 8}{1} = - 64[/tex]