Explications étape par étape:
A = 14 / 9
A= 49X 10 / 15 X 21
A = 490 / 315
A = 14 / 9
B = - 16 / 3
B = - 28 X 36 / 27 X 7
B = - 1008 / 189
B = - 1008 / 189
B = - 16 / 3
C = 2
C = 5 X 66 / 11 X 15
C = 2
D = 6 / 5
D = - 14 / 25 ( - 15 / 7 )
D = 210 /175
D = 6 / 5