Réponse:
a) (3x + 5) + (4x - 2)
= 3x +5 +4x -2
= 3x +4x +5 -2
= 7x +3
b) (10x + 3) - (4x + 8)
= 10x +3 -4x -8
= 10x -4x +3 -8
= 6x -5
c) (-9x + 1) + (4 - 5x)
= -9x +1 +4 -5x
= -9x -5x +1 +4
= -14x +5
d) (x - 7) - (4x - 3)
= x -7 -4x +3
= x -4x -7 +3
= -3x -4
