Quelqu'un peut maidé svp urgent !

Bonjour,

A = 2/3 - 7/3 x 8/21
A = 2/3 - 56/93
A = 2 x 31 / 3 x 31 - 56/93
A = 62/93 - 56/93
A = 6/93
A = 3 x 2 / 3 x 31
A = 2/31

B = (3/4 - 5/6) x 3/2
B = (3 x 6 / 4 x 6 - 5 x 4 / 6 x 4) x 3/2
B = (18/24 - 20/24) x 3/2
B = - 2/24 x 3/2
B = - 6/48
B = 6 x - 1 / 6 x 8
B = - 1/8

C = 11 : (2/3 - 5/2)
C = 11 : (2 x 2 / 3 x 2 - 5 x 3 / 2 x 3)
C = 11 : (4/6 - 15/6)
C = 11 : - 11/6
C = 11 x - 6/11
C = - 66/11
C = 11 x - 6 / 11 x 1
C = - 6

D ; E ; F on ne les voit pas en entier