Answer & Step-by-step explanation:
[tex]9-(-3)[/tex]
Two negatives makes a positive, so change the symbol to a positive:
[tex]9+3=12[/tex]
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[tex]-1-(-2)[/tex]
Two negatives makes a positive, so change the negative 1 'minus negative' two to an addition sign:
[tex]-1+2=1[/tex]
