Bonjour,
A = 13/7 - (4/3 + 11/21)
A = (13 x 3) / (7 x 3) - [(4 x 7) / (3 x 7) + 11/21]
A = 39/21 - (28/21 + 11/21)
A = 39/21 - 39/21
A = 0
B = (- 5/4) x (- 4/7) x (11/15)
B = 20/28 x 11/15
B = 220/420
B = (20 x 11) / (20 x 21)
B = 11/21
C = (3 - 2/3) / (- 4/7 x 14/3)
C = [(3 x 3) / (1 x 3) - 2/3] : - 56/21
C = (9/3 - 2/3) : - 56/21
C = 7/3 x - 21/56
C = - 147/168
C = (21 x - 7) / (21 x 8)
C = - 7/8
D = - 9/2 + 4/5 x (- 10/16)
D = - 9/2 - 40/80
D = - 9/2 - (40 x 1) / (40 x 2)
D = - 9/2 - 1/2
D = - 10/2
D = (2 x - 5) / (2 x 1)
D = - 5
E = 11/20 - (- 4/3) x (- 21/80)
E = 11/20 - 84/240
E = 11/20 - (12 x 7) / (12 x 20)
E = 11/20 - 7/20
E = 4/20
E = (4 x 1) / (4 x 5)
E = 1/5.
