I also get about $16^o$.

First there is absolutely no need to find the point of intersection.

The direction vector of the line is $\vec{D}=<2,-1,2>$. The normal to the plane is $\vec{N}=<1,2,1>$.

The angle between the line and the plane is $\dfrac{\pi}{2}-\arccos\left(\dfrac{|\vec{D}\cdot\vec{N}|}{\|\vec{ D}\|~\|\vec{N}\|}\right)$

See the calculation here.