-7+(-15,6+15,6) 9,7+(0+(-9,7))

Question

-7+(-15,6+15,6)

9,7+(0+(-9,7))

Answer 1

-7+(-15,6+15,6)=-7
9,7+(0+(-9,7)=0

Answer 2

1) -7+(0)=-7
2)  9,7+(0-9,7)=9,7-9,7=0