Vectors in Space · Easy problem

Let $\mathbf u = (4, 2, 1)$ and $\mathbf v = (0, 3, 4)$. Find the $z$-component of the vector projection $\operatorname{proj}_{\mathbf v}\mathbf u = \dfrac{\mathbf u \cdot \mathbf v}{\mathbf v \cdot \mathbf v}\,\mathbf v$.