Réponse:
E=3+15-23-17-12
=18-52
E=-34
D=-4+(-3)-5-3+(-2)
=-4-3-5-3-2
D=-17
C=-14-14+30+(-15)-(-20)
=-28+30-15+20
=-28-15+30+20
=-43+50
C=7
B=-5+(-4)-15-(-6)+7
=-5-4-15+6+7
=-24+11
B=-13
A=2+(-7)+7+(-12)+(-5)+4+(-2)
= 2-7+7-12-5+4-2
=+7+4-12-5-7-2
=11-26
A =-15