Answer:
[tex]\Huge \boxed{0 }[/tex]
[tex]\rule[225]{225}{2}[/tex]
Step-by-step explanation:
[tex]\Longrightarrow \ (-9)+9[/tex]
Combining the numbers:
[tex]\Longrightarrow \ 9-9[/tex]
[tex]\Longrightarrow \ 0[/tex]
