aidé moi svp lige 2 et 3 svp merci d avance

2)
D = 11/12 + 7/4
D = 11/12 + 7 x 3 / 4 x 3
D = 11/12 + 21/12
D = 32/12
D = 4 x 8 / 4 x 3
D = 8/3

E = 5/21 + 1/14
E = 5 x 2 / 21  x 2 + 1 x 3 / 14 x 3
E = 10/42 + 3/42
E = 13/42

F = 5/4 - 1/6
F = 5 x 6 / 4 x 6 - 1 x 4 / 6 x 4
F = 30/24 - 4/24
F = 26/24
F = 2 x 13 / 2 x 12
F = 13/12

G = 3/8 - 1/5
G = 3 x 5 / 8 x 5 - 1 x 8 / 5 x 8
G = 15/40 - 8/40
G = 7/40

3)
A = 5/18 + - 5/8
A = 5/18 - 5/8
A = 5 x 8 / 18 x 8 - 5 x 18 / 8 x 18
A = 40/144 - 90/144
A = - 50/144
A = 2 x - 25 / 2 x 72
A = - 25/72

B = 7/12 - 5/9
B = 7 x 3 / 12 x 3 - 5 x 4 / 9 x 4
B = 21/36 - 20/36
B = 1/36

C = 2/15 + - 6/25
C = 2/15 - 6/25
C = 2 x 5 / 15 x 5 - 6 x 3 / 25 x 3
C = 10/75 - 18/75
C = - 8/75

D = 1/6 + 3/5
D = 1 x 5 / 6 x 5 + 3 x 6 / 5 x 6
D = 5/30 + 18/30
D = 23/30