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> The point $Q$ is the image of the point $P(1, 5)$ about the line $y = x$ and $R$ is the image of the point $Q$ about the line $y=−x$. The circumcenter of the $ΔPQ$R is-
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Answer given is $(0,0)$

My attempt:

Replection of $(1,5)$ in $y=x$ is $(5,1)$ and in $y=-x$ is $(-5,-1)$. Now I don't see why origin is the circumcenter.