Je n'arrive pas non plus !! A la question -5|21+ -2|3 =

-5/21 + - 2/3
= -5/21 - 2/3
= -5/21 - 2 x 7 / 3 x 7
= -5/21 - 14/21
= - 19/21

[tex] \frac{-5}{21} - \frac{2}{3} = \frac{-5}{21} - \frac{7*2}{7*3} = \frac{-5}{21} - \frac{14}{21} = \frac{-19}{21} [/tex]