# Prime and Composite Possibilities

Number Theory Level 3

Let $$x$$ be a positive integer which can be written as $$a \times b$$, where $$a$$ and $$b$$ are primes (positive). We define $$x_=ab\left(1-\frac{1}{a}\right)\left(1-\frac{1}{b}\right)$$. Find the sum of all possible values of $$x$$ such that $$x_=600$$

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