Bonjour,
A = 2/3 + 5/3
A = 7/3
B = 15/3 - 2/9
B = 15 x 3 / 3 x 3 - 2/9
B = 45/9 - 2/9
B = 43/9
C = 2/4 + 3/8 + 1/2
C = 2 x 2 / 4 x 2 + 3/8 + 1 x 4 / 2 x 4
C = 4/8 + 3/8 + 4/8
C = 11/8
D = (2 + 3) x 4/5 + 7 + 4/12
D = 5 x 4/5 + 7 + 4/12
D = 20/5 + 7 x 60 / 1 x 60 + 4 x 5 / 12 x 5
D = 20 x 12 / 5 x 12 + 420/60 + 20/60
D = 240/60 + 440/60
D = 680/60
D = 20 x 34 / 20 x 3
D = 34/3
E = (2 + 5) (5 - 3) / 21 - 4/3
E = 7 x 2
21 x 3 / 1 x 3 - 4/3
E = 14
63/3 - 4/3
E = 14 : 59/3
E = 14 x 3/59
E = 42/59