Bonjour
A = - 1/15 + 3/20
A = (- 1 x 4) / (15 x 4) + (3 x 3) / (20 x 3)
A = - 4/60 + 9/60
A = 5/60
A = (5 x 1) / (5 x 12)
A = 1/12
B = 4/7 + (- 1/15)
B = (4 x 15) / (7 x 15) - (1 x 7) / (15 x 7)
B = 60/105 - 7/105
B = 53/105
C = - 5/12 + 4/15
C = (- 5 x 5) / (12 x 5) + (4 x 4) / (15 x 4)
C = - 25/60 + 16/60
C = - 9/60
C = (3 x - 3) / (3 x 20)
C = - 3/20
D = - 2/15 - 3/10
D = (- 2 x 2) / (15 x 2) - (3 x 3) / (10 x 3)
D = - 4/30 - 9/30
D = - 13/30
E = - 11/20 + 7/12
E = (- 11 x 3) / (20x 3) + (7 x 5) / (12 x 5)
E = - 33/60 + 35/60
E = 2/60
E = (2 x 1) / (2 x 30)
E = 1/30
F = - 2/11 - 5/33
F = (- 2 x 3) / (11 x 3) - 5/33
F = - 6/33 - 5/33
F = - 11/33
F = (11 x - 1) / (11 x 3)
F = - 1/3
