In lesson 4.9, there is the sentence
Scrivete cartoline spesso per la tua zia in Germania?
translating to Do (you) write postcards often for (your) aunt in Germany?
In the flashcards we are given the hint “P” (plural), which seems consistent with scrivete. But then we have la tua zia, which is the singular possessive adjective.
Could I ask why it isn't la vostra zia ?