Răspuns :
(-16)+(-4)=-20
(-10)+(-10)=-20
(-3)+(-17)=-20
(-30)+(+10)=-20
(-45)+(+25)=-20
-4-4-4-4-4=-20; -2-4-6-6-2=-20; -1-3-6-2-8=-20; -5-3-2-8-2=-20; -7-1-3-4-5=-20