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How to align (9) A to right?

\item [Hlavní poloosa] (9) A \\
$a$ může být určena 

marked as duplicate by Werner, Phelype Oleinik, Stefan Pinnow, Mensch, user36296 Nov 28 '18 at 23:08

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\item [Hlavní poloosa] \hfill(9) A \\

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