Q86. Let $A$ be a $3 \times 3$ matrix of non-negative real elements such that $A \left[ \begin{array} { l } 1 \\ 1 \\ 1 \end{array} \right] = 3 \left[ \begin{array} { l } 1 \\ 1 \\ 1 \end{array} \right]$. Then the maximum value of $\operatorname { det } ( \mathrm { A } )$ is $\_\_\_\_$\\