Declension designs are made use of to apply the proper declension combos to any determiner and/or adjective preceding a noun. You must use ‘der Junge’ to state ‘the boy during the nominative case and after that use ‘den Jungen’ while in the accusative scenario. ‘Dem Jungen’ suggests the dative scenario. https://web-hinweis.de/die-grundlagen-des-gesellschaftsrechts-den-rechtsrahmen-fur-unternehmen-verstehen/