Answers

2015-06-25T22:39:50+08:00
Because negative (negative) = positive   -x (-x) = x
"          " postive (positive)    = positive  x (x)    = x
"          " negative (postivive) = negative  -x (x)  = -x

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2015-06-27T00:39:09+08:00
The answer is negative 9...
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