The line is perpendicular to normal, hence the line is parallel to plane, so the reflected line has the same direction.
Now, image of $\left(\mathrm{2,1},1\right)$ in the plane is $\left(\alpha ,\beta ,\gamma \right)$ say, then
$\frac{\alpha -2}{1}=\frac{\beta -1}{1}=\frac{\gamma -1}{1}=\frac{-2\left(4-7\right)}{1+1+1}=2$
So, the point is $\left(\mathrm{4,3},3\right)$