Given the expression:
[tex]-7-(-9)[/tex]we know as a general rule that if a negative sign is outside of a parenthesis (or any symbol that groups numbers), then the sign of what's inside will change, then we have the following:
[tex]-7-(-9)=-7+9[/tex]On the number line, this addition looks like this:
notice that we have to move 9 units to the right, therefore, Marisa is not correct.
