Answer:
1. -2=-x - 9, 7=-x, -7=x
2. -1=-x - 9, 8=-x, -8=x
3. 0=-x - 9, 9=-x, -9=x
4. 1=-x - 9, 10=-x, -10=x
5. 2=-x - 9, 11=-x, -11=x
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