Question

calcular:

1. -5-( +11 )-(-20)=
2. 9-[(-5)-(+7)]=
3. -7-[(-3)-(- 9)]=

Answer 1

1.). -5-(+11)-(-20)=-5-11+20=-16+20=4
2.). 9-[(-5)-(+7)]= 9-[-5-7]=9-[-12]=9+12=21
3.). -7-[(-3)-(-9)]= -7-[(-3)+9]=-7-[6]=-13