Let a =3 i + j - k and c =2 i -3 j +3 k. If b is a vector such that a = b × c and | b |^2=50, then |72-| b + c |^2| is equal to ____.

Let $\displaystyle \vec{a}=3 \hat{i}+\hat{j}-\hat{k}$ and $\displaystyle \vec{c}=2 \hat{i}-3 \hat{j}+3 \hat{k}$. If $\displaystyle \vec{b}$ is a vector such that $\displaystyle \vec{a}=\vec{b} \times \vec{c}$ and $\displaystyle |\vec{b}|^2=50$, then $\displaystyle \left|72-|\vec{b}+\vec{c}|^2\right|$ is equal to $\displaystyle \_\_\_\_$.