Sagot :

dbaloki

Réponse:

B=(3/5-1/2)×5/2

=(3×2-5×1/5×2)×5/2

=(6-5/10)×5/2

=(1/10)×5/2

=1/10×5/2

=5/20

=5:5=1

=20:5=4 donc B=1/4

D=2/3+7/3:21/8

=2+7/3:21/8

=9/3:21/18

=9/3/grande barre 21/8

=9/3×8/21=9×8/21×3=72/63

=72:9=8

=63:9=7

donc D=8/7