15 2.8 The Mystery X Puzzle
The centre number of each square is found by using the order of operations on the numbers that surround it. The challenge is to solve for the variable 
![\[\begin{tabular}{|c|c|c|} \hline \begin{array}{ccc}&5& \\ \\ &\textbf{21}& \\ \\ 3&&6\end{array}& \begin{array}{ccc}&3& \\ \\ &\textbf{42}& \\ \\ 11&&9\end{array}& \begin{array}{ccc}&12& \\ \\ &\textbf{64}& \\ \\ 5&&X\end{array}\\ \hline \end{tabular}\]](https://kpu.pressbooks.pub/app/uploads/quicklatex/quicklatex.com-59081d340f1358a1a0feae3381810b6b_l3.png "Rendered by QuickLaTeX.com")
Can you solve for 
? Can you find any other possible solution?
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