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# Super Hard

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$$\begin{array}{| *5{@{}c@{}|}} \hline \qquad & \qquad & \qquad & \textcolor{red}{\heartsuit} & \qquad \\ \hline & 74 & & \qquad & \\ \hline & & & & 186 \\ \hline & & 103 & & \\ \hline 0 & & & & \\ \hline \end{array}$$

It is possible to place positive integers into the vacant twenty-one squares of this $$5 \times 5$$ grid so that the numbers in each row and column form an arithmetic sequence. Find the number that must occupy the vacant square marked by the $$\textcolor{red}{\heartsuit}$$.

Feb 1, 2019