This is the 16821st most frequent Polish word.
wykonanych
"Wykonanych" means "performed," "executed," or "completed" (past participle, plural, genitive or accusative form).
The word 'wykonanych' here is used in the past participle form to describe tasks that have been completed.
Wszystkie zadania zostały wykonane z największą starannością.
All tasks were executed with utmost care.
'wykonanych' acts as an attributive adjective describing the 'prac' (works) as those that were completed.
Zdjęcia wykonanych prac zostały załączone do raportu.
Photos of completed works were attached to the report.
Here, 'wykonanych' relates to 'testów' (tests), specifying them as those that have been conducted or completed.