28. (5 points)
The Magic Academy has an operation rule: \begin{tabular}{|l|l|} \hline$a$ & $b$ \\ \hline$c$ & $d$ \\ \hline \end{tabular}$=(\overline{a b}+\overline{c d})-(\overline{a c}+\overline{b d})$, where $a, b, c, d$ are all digits from 1 to 9, for example: when the array $(a, b, c, d)$ is $(2,2,3,4)$,
\begin{tabular}{|l|l|}
\hline 2 & 2 \\
\hline 3 & 4 \\
\hline
\end{tabular}$=(22+34)-(23+24)=9$

According to this rule, the number of possible arrays $(a, b, c, d)$ that can make the operation result 45 is $\qquad$.
$324$