Bonjour !
A = 2/3 + 7/3 * (-9)/4
A = 2/3 + (7*(-9)) / (3*4)
A = 2/3 - 63/12
A = (2*4)/(3*4) - 63/12
A = 8/12 - 63/12
A = (8 - 63) / 12
A = -55/12
B = (2 - 5/8) : 3/4
B = (16/8 - 5/8) * 4/3
B = ((16-5)/8) * 4/3
B = 11/8 * 4/3
B = (11*4) / (8*3)
B = 44/24
B = 11/6
C = (4/5 - 2) * (3/4 - 2/3)
C = (4/5 - 10/5) * [(3*3)/(4*3) - (2*4)/(3*4)]
C = [(4-10)/5] * (9/12 - 8/12)
C = (-6)/5 * (9-8) / 12
C= (-6)/5 * 1/12
C = (-6 * 1) / (5 * 12)
C = -6/60
C = -1/10
D = 2/13 - 5/13 : 10/6
D = 2/13 - 5/13 * 6/10
D = 2/13 - (5*6) / (13*10)
D = 2/13 - 30/130
D = 2/13 - 3/13
D = (2 - 3) / 13
D = -1/13
J'espère t'avoir aidé. Bon courage !
