Question 77777
Your answer of x = -16 is correct.
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Your "check" is:
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5(-16) + 8 + 3(-16) -16 + 5 = 6(-16) - 3
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The first three terms [5(-16) + 8 + 3(-16)] are correct.  The next term should be -(-16) = +16
not -16.  All the rest is OK.
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Your check should further simplify to:
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-80 + 8 - 48 + 16 + 5 = -96 - 3
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and if you add the terms on each side you get - 99 = - 99
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Hope this eases your mind.  Just a minor error.