Bonsoir,

A = (2/3 + 9) / (- 9/2 + 9)

A = [2/3 + (9 x 3) / (1 x 3)] : [- 9/2 + (9 x 2) / (1 x 2)]

A = (2/3 + 27/3) : (- 9/2 + 18/2)

A = 29/3 : 9/2

A = 29/3 x 2/9

A = 58/27

B = 9/7 : (- 1/10 - - 1/7)

B = 9/7 : [(- 1 x 7) / (10 x 7) + (1 x 10) / (7 x 10)]

B = 9/7 : (- 7/70 + 10/70)

B = 9/7 : 1/70

B = 9/7 x 70

B = 630/7

B = (7 x 90) / (7 x 1)

B = 90.

C = - 12/11 + 20/11 : 16/11

C = - 12/11 + 20/11 x 11/16

C = (- 12 x 16) / (11 x 16) + 220/176

C = - 192/176  + 220/176

C = 28/176

C = (4 x 7) / (4 x 44)

C = 7/44.