bonsoir j'ai un devoir pour demain aidez-moi svp.

Réponse:

A=(21/-4)//(35/12)

=(21/-4)*(12/35)

=(-3)*(3/5)

=-9/5

B=(-5/4)//10

=(-5/4)*(1/10)

=(-1/4)*(1/2)

=-1/8

C=(12)//(-4/9)

=12*(-9/4)

=3*(-9)

=-27

D=(3-(9/2))//((6/5)+3)

=((6-9)/2)//((6+15)/5)

=(-3/2)//(21/5)

=(-3/2)*(5/21)

=(-1/2)*(5/7)

=-5/14

E=(5-1/4)//(-2*5/3)

=((20-1)/4)//(-10/3)

=(19/4)//(-10/3)

=(19/4)*(-3/10)

=(19*(-3))//(4*10)

=-57/40

F=((3/2)+((5*3)/2))//(((7/3)-(1/6))*(-5/2))

=((3/2)+(15/2))//(((14-1)/6)*(-5/2))

=(18/2)//((13/6)*(-5/2))

=(9)//((13*-5)//(6*2))

=(9) //(-65/12)

=9*(-12/65)

=-108/65