Bonsoir
A = 2/3 + 7/3 x (-9/4)
A = 2/3 - 9/3 x 7/4
A = 2/3 - (3 x 3)/3 x 7/4
A = 2/3 - 3 x 7/4
A = 2/3 - 21/4
A = (2 x 4)/(3 x 4) - (21 x 3)/(4 x 3)
A = 8/12 - 63/12
A = -55/12
B = (2 - 5/8) : 3/4
B = [(2 x 8)/8 - 5/8] x 4/3
B = (16/8 - 5/8) x 4/3
B = 11/8 x 4/3
B = 11/3 x 4/8
B = 11/3 x 1/2
B = 11/6
C = (4/5 - 2) x (3/4 - 2/3)
C = (4/5 - 10/5) x (9/12 - 8/12)
C = (-6/5) x 1/12
C = -6/12 x 1/5
C = -1/2 x 1/5
C = -1/10
D = 2/13 - 5/13 : 10/16
D = 2/13 - 5/13 x 16/10
D = 2/13 - 5/13 x 8/5
D = 2/13 - 5/5 x 8/13
D = 2/13 - 8/13
D = -6/13