Bonjour,
A = - 2/21 x 14/5 - 8/5
A = - 28/105 - 8/5
A = - 28/105 - (8 x 21) / (5 x 21)
A = - 28/105 - 168/105
A = - 196/105
A = (7 x - 28) / (7 x 15)
A = - 28/15
B = 1/4 + 5/3 x - 1/8
B = 1/4 - 5/24
B = (1 x 6) / (4 x 6) - 5/24
B = 6/24 - 5/21
B = 1/24
C = 4/- 3 + - 7/6 x - 2/5
C = - 4/3 + 14/30
C = (- 4 x 10) / (3 x 10) + 14/30
C = - 40/30 + 14/30
C = - 26/30
C = (2 x - 14) / (2 x 15)
C = - 14/15.
D = (8/15 - 7/5) x (- 1/6 + 2/9)
D = [8/15 - (7 x 3) / (5 x 3)] x [(- 1 x 3) / (6 x 3) + (2 x 2) / (9 x 2)]
D = (8/15 - 21/15) x (- 3/18 + 4/18)
D = - 13/15 x 1/18
D = - 13/270
