Why was this marked wrong? Looks OK to me: למה הוא יושב איפה שחתולי יושב?
Maybe because you didnt put the article שהחתול
No, when a noun has a pronominal suffix the noun is always definite.
That's what I put too, but the comment below says this way of identifying possession is quite formal and really used only with a few nouns.
lama hu yoshev eifo sh-ha-khatul sheli yoshev
The correct text for me shows היכן. I have not seen that word before. When do I use במקום היכן איפה?
Are מדוע and למה interchangeable?
It's formal, מדוע.
Also I wrote למה הוא יושב איפה שהחתולה שלי יושב and it told me the ה at the end of cat was a typo, but since the cat's gender is unknown, shouldn't that be acceptable?
It should also be יושבת in that case.
that's right thanks, that's probably why שהחתולה it marked as a typo, thanks again
What's wrong with using חתולי
That construct (genitive) is not used much in modern Hebrew outside of a few nouns such as family members (אחי, אבי). It is used in a formal way, Biblical Hebrew and literature. "שלי" is the common "my"