Bonjour,
A = 2/3 + 7/3 x - 9/4
A = 2/3 - 63/12
A = (2 x 4) / (3 x 4) - 63/12
A = 8/12 - 63/12
A = - 55/12
B = (2 - 5/8) : 3/4
B = [(2 x 8) / (1 x 8) - 5/8] : 3/4
B = (16/8 - 5/8) : 3/4
B = 11/8 x 4/3
B = 44/24
B = (4 x 11) / (4 x 6)
B = 11/6
C = (4/5 - 2) x (3/4 - 2/3)
C = [4/5 - (2 x 5) / (1 x 5)] x [(3 x 3) / (4 x 3) - (2 x 4) / (3 x 4)]
C = (4/5 - 10/5) x (9/12 - 8/12)
C = - 6/5 x 1/12
C = - 6/60
C = (6 x - 1) / (6 x 10)
C = - 1/10.
D = 2/13 - 5/13 : 10/16
D = 2/13 - 5/13 x 16/10
D = (2 x 10) / (13 x 10) - 80/130
D = 20/130 - 80/130
D = - 60/130
D = (10 x - 6) / (10 x 13)
D = - 6/13.
