Two Similar Fractions

Algebra Level 4

If $$\dfrac{(p-q)(r-s)}{(q-r)(s-p)}=2015$$, the value of $$\dfrac{(p-r)(q-s)}{(p-q)(r-s)}$$ can be written as $$\frac{a}{b}$$ where $$a$$ and $$b$$ are coprime integers. Find $$a+b$$.

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