Bonsoir pouvez vous m’aider pour l’exercice 4 niveau 3 eme svp

5/4×3/2

=15/8

21/8×(-2/7)

=-42/56

=-(42÷14)/(56÷14)

=-3/4

9/2×8/27

=72/54

=(72÷18)/(54÷18)

=4/3

3/2÷(-8/9)

=3/2×(-9/8)

=-27/16

-1/4÷15/2

=-1/4×2/15

=-2/30

=(-2÷2)/(30÷2)

=-1/15

18/5÷2/25

=18/5×25/2

=450/10

=(450÷10)/(10÷10)

=45