Bonjour
A = x + (x - 4) / 2
A = 2x/2 + (x - 4) / 2
A = (2x + x - 4) / 2
A = (x - 4) / 2
B = 3 - (x - 1) / 4
B = 12/4 - (x - 1) / 4
B = (12 - x - 1) / 4
B = (- x + 11) / 4
C = (3x - 2) / 8 - (5x + 1) / 6
C = (9x - 6) / 24 - (20x + 4) / 24
C = (9x - 6 - 20x - 4) / 24
C = (- 11x - 10) / 24.