Vector Algebra

If $7 \hat{\mathbf{i}}-4 \hat{\mathbf{j}}+5 \hat{\mathbf{k}}$ is the position vector of the vertex $A$ of a tetrahedron $A B C D$ and $-\hat{\mathbf{i}}+4 \hat{\mathbf{j}}-3 \hat{\mathbf{k}}$ is the position vector of the centroid of the $\triangle B C D$, then the position vector of the centroid of the tetrahedron $A B C D$ is