Question

What integer is the opposite of 9?

Answer 1

The opposite of a number is just the number on the opposite side of zero on the number line. For example the opposite of a is -a. The opposite of -a is a.The integer that is the opposite of 9 is -9. 
Hope this helped!

Answer 2

The integer oppisite of 9 is -9/negitive 9. On a number line I would look like this,

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-13-12-11-10-9-8-7-6-5-4-3-2-1 0 1 2 3 4 5 6 7 8 9 10 11 12 13
                   --                                                       --