Breakdown of Ein höflicher Mitarbeiter hilft uns bei einem neuen Konto.
ein
a, an (eine)
neu
new
uns
us
helfen
to help
Questions & Answers about Ein höflicher Mitarbeiter hilft uns bei einem neuen Konto.
Why does the adjective neu end in -en (neuen) instead of -em?
In this sentence, einem is already showing us the case and gender (dative, neuter). When an indefinite article like einem clearly shows the case, the adjective that follows it gets the standard dative ending, which is always -en. So we say bei einem neuen Konto.
Then why does höflicher end in -er at the beginning of the sentence?
Because ein Mitarbeiter is the subject of the sentence (nominative case). The word ein doesn't show the masculine gender on its own here because it has no ending. Since the article doesn't show the gender, the adjective has to step up and show it by taking the masculine -er ending: ein höflicher Mitarbeiter.
Why is the phrase einem neuen Konto in the dative case?
It is because of the preposition bei (with/at/by). In German, bei is a strict dative preposition, meaning whatever noun phrase comes directly after it must always take the dative case.
Why is uns used here, and what case is it?
The word uns means 'us', and here it is in the dative case. The verb helfen (to help) always forces the person being helped into the dative case. Luckily, uns is exactly the same in both dative and accusative!