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\begin{document}

\begin{tabular}{|c|l|l|l|}
\hline
\thead{Nr\_faktury} & \thead{Imię} & 
\thead{Nazwisko} & \thead{Zamówienie} \\\hline
2025007 & Adam & Kowalski &
\gape{\begin{tabular}{|c|l|l|l|}
\hline
\thead{Nr} & \thead{Nazwa} & \thead{Cena} & \thead{Sztuk} \\\hline
1 & mleko & 4,50 & 12 \\
2 & mąka & 3,20 & 10 \\\hline
\end{tabular}} \\\hline
2025012 & Ewa & Nowak &
\gape{\begin{tabular}{|c|l|l|l|}
\hline
\thead{Nr} & \thead{Nazwa} & \thead{Cena} & \thead{Sztuk} \\\hline
1 & czekolada & 6,20 & 10 \\
2 & lody & 16,50 & 4 \\
3 & jogurt & 2,60 & 12 \\\hline
\end{tabular}} \\\hline
\end{tabular}

\end{document}