SOLUTION: When an unknown number is decreased by 15, the result is twice the opposite of that number. Find the mystery number.

SOLUTION: When an unknown number is decreased by 15, the result is twice the opposite of that number. Find the mystery number.

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Question 1189478: When an unknown number is decreased by 15, the result is twice the opposite of that number. Find the mystery number.
Answer by ikleyn(52914) (Show Source): You can put this solution on YOUR website!
.


    x - 15 = 2*(-x)


    x - 15 = -2x


    x + 2x = 15


      3x   = 15


       x   = 15/3 = 5.     ANSWER

Solved with all necessary explanations.

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