Réponse:
Exercice n°1:
(+6) + (-8) = 6-8 = -2
(-90)+(-6) = -90-6= -96
(-7) + (+4)= -7 +4 = -3
(-19) + (-19) = -19 -19 = -38
(472) + (-1.8)= 470.2
(-9,6)+(-6,8)= -16.4
A =(+7)+(-4)+(-2)+(-8) = 7 -14 = -7
B=(-8) + (+4) + (-10) + (+6) = -18 + 10 = -8
C=(-12)+(-7)+(-19) + (-9) = -38 -9 = -47
+(-7)-(19) = -7 -19 = -26
(-4)-(-7) = -4 +7 = 3
(+7)-(+7) = 7 -7=0
D=(-7)(+8)-(9) = -56 -9 = -65
la plupart du temps c'est illisible donc j'ai pas tout fais