Reflection of a vector across a line

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For homework, I need to find the reflection of the vector <1,1,1> over the line defined by all the scalar multiples of <2,1,2>. I tried looking at the other questions about similar topics here, but they didn't help me. Could anyone give me a hint on how I am supposed to do this?

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Hint: Find the projection $\vec{p}$ of $\vec{u}=\langle1,1,1\rangle$ on $\vec{w}=\langle 2,1,2\rangle$, and then use that the reflection $\vec{r}$ satisfies $\vec{r}+\vec{u}=2\vec{p}$.