Question 200088
Suppose the unknown number is x.
Then the opposite of the number is -x.
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Three time the opposite of the unknown number is -3x.
Five times the unknown number is 5x.
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As their difference is 40, we have
-3x - 5x = 40
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Solving for x, we have
-8x = 40
x = -5
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So the number is -5.