Aidez moi pour l'exercice 1 svp :

A = (1/3 + 2) - (5/6 - 1/2)
A = (1/3 + 2 x 3 / 1 x 3) - (5/6 - 1 x 3 / 2 x 3)
A = (1/3 + 6/3) - (5/6 - 3/6)
A = 7/3 - 2/6
A = 7 x 2 / 3 x 2 - 2/3
A = 14/6 - 2/6
A = 12/6
A = 6 x 2 / 6 x 1
A = 6

B = 7/15 - 8/15 (3 - 5/2)
B = 7/15 - 8/15 (3 x 2 / 1 x 2 - 5/2)
B = 7/15 - 8/15 (6/2 - 5/2)
B = 7/15 - 8/15 (1/2)
B = 7 x 2 / 15 x 5 - 8/30
B = 14/30 - 8/30
B = 6/30
B = 6 x 1 / 6 x 5
B = 1/5

C = 6/5 x 15/24 + 5/3 + 2
C = 90/120 + 5/3 + 2
C = 9 x 10 / 12 x 10 + 5/3 + 2
C = 9/12 + 5/3 + 2
C = 9/12 + 5 x 4 / 3 x 4 + 2 x 12 / 1 x 12
C = 9/12 + 20/12 + 24/12
C = 53/12

D = 8/21 x 7/18 x 9/2
D = 56/378 x 9/2
D = 504/756
D = 252 x 2 / 252 x 3
D = 2/3