Vector Algebra

Let \(\vec{a}=\hat{i}-\hat{j}+2 \hat{k}\) and let \(\vec{b}\) be a vector such that \(\vec{a} \times \vec{b}=2 \hat{i}-\hat{k}\) and \(\vec{a} \cdot \vec{b}=3\). Then the projection of \(\vec{b}\) on the vector \(\vec{a}-\vec{b}\) is :