Explications étape par étape:
A = 2- x - x +2
A = -2x + 4
B = -3 - y + 5 - 8y
B = 2 - 9y
C = 1 - 5x + 6 + 2x
C = 7 - 3x
D = - 2 + 3y - 5 - 7y
D = - 7 - 4y
E = 7 - 4x + 8 + 6 + 2x
E = 21 - 2x
