The answer is D.
(rotation 180 degrees about the origin)
Answer:
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Let's call the number we're looking for . We know that is twice as much as .
Twice as much as a number simply means the double of that number, and in turn the double of a number means to muliply that number by 2.
So, in order to obtain , you have to multply by 2. In formula, you have
or simply