I’m trying to translate this sentence:
Vos nobis de voluptatibus adulescentiae tum scripsistis.
I believe Vos is in the nominative case, but nobis is tough I’m not sure if it’s dative or ablative. de voluptatibus I know translates to “from pleasure” because volu… is in the ablative. I’m not sure if adulescentiae is in the genitive case or dative. Finally, I know tum is “then” and scripsistis translates to “you have written” in plural form. My problem is ordering sentences properly after I translate them to english.
You are correct that vos is in the nominative, further enforced by the second person plural verb. The possibilities for an ablative of a personal pronoun are rather limited, almost nonexistant without a preposition - nobis makes most sense as a dative “to us”. de can mean “from”, but more often (and in this case) “about”. adulescentiae wouldn’t really make sense in the dative… “you wrote to adulescence”… much more likely as a genitive, especially since there is already an indirect object in this sentence (nobis).
A word-for-word translation of this sentence should make sense, though some rearrangement of the words will produce a better English sentence:
Vos ‘you’
nobis ‘to us’
de ‘about’
voluptatibus ‘pleasures’
adulescentiae ‘of youth’
tum ‘then’
scripsistis ‘wrote’
No problem. The ability to deduce the correct case when there are multiple possibilities comes with experience. Logic will usually guide you there, but it takes some getting used to. It also requires your ability to accurately recognize the declensions/cases, but you do not seem to have a problem in that area from what I can see.