Bonsoir
A = 1 - (1/3 + 1/4)
A = (1 x 12) / (1 x 12) - [(1 x 4) / (3 x 4) + (1 x 3) / (4 x 3)]
A = 12/12 - (4/12 + 3/12)
A = 12/12 - 7/12
A = 5/12
B = 1 - (1/3 + 1/6 + 1/9)
B = (1 x 18) / (1 x 18) - [(1 x 6) / (3 x 6) + (1 x 3) / (6 x 3) + (1 x 2) / (9 x 2)]
B = 18/18 - (6/18 + 3/18 + 2/18)
B = 18/18 - 11/18
B = 7/18
C = - 4/3 - (5/6 - 1/4)
C = (- 4 x 4) / (3 x 4) - [(5 x 2) / (6 x 2) - (1 x 3) / (4 x 3)]
C = - 16/12 - (10/12 - 3/12)
C = - 16/12 - 7/12
C = - 23/12
D = 1/5 - (- 1/15 + 3/25) + 2/3
D = (1 x 15) / (5 x 15) - [(- 1 x 5) / (15 x 5) + (3 x 3) / (25 x 3)] + (2 x 25) / (3 x 25)
D = 15/75 - (- 5/75 + 9/75) + 50/75
D = 15/75 - 4/75 + 50/75
D = 61/75.
