bonjour,pouvez vous m'aidez svp ex 13.merci d'avance

Bonjour,

A = 7/24 - 5/8
A = 7/24 - 5 x 3 / 8 x 3
A = 7/24 - 15/24
A = - 8/24
A = 8 x - 1 / 8 x 3
A = - 1/3

B = - 5/18 - 11/6
B= - 5/18 - 11 x 3 / 6 x 3
B = - 5/18 - 33/18
B = - 38/18
B = 2 x - 19 / 2 x 9
B = - 19/9

C = 11/45 - - 5/9
C = 11/45 + 5/9
C = 11/45 + 5 x 5 / 9 x 5
C = 11/45 + 25/45
C = 36/45
C = 9 x 4 / 9 x 5
C = 4/5

D = - 8/7 + - 10/21
D = - 8/7 - 10/21
D = - 8 x 3 / 7 x 3 - 10/21
D = - 24/21 - 10/21
D = - 34/21