\begin{tabular}{|l|l|l|l||} 
\hline 
$x$  &  $f(x)$ &  $x$ &  $f(x)$ \\ \hline 
1    &       4 &    6 &      39 \\ \hline 
2    &       7 &    7 &      52 \\ \hline 
3    &      12 &    8 &      67 \\ \hline 
4    &      19 &    9 &      84 \\ \hline 
5    &      28 &   10 &     103 \\ \hline 
\end{tabular}