"These are my rooms" should also be acceptable, correct?
Эти — мои комнаты.
This looks wrong, это - мои комнаты would be more correct.
So to clarify,
это - мои комнаты = THESE are MY ROOMS
Эти комнаты - мои = THESE ROOMS are MINE
I wonder why it's not. I got it wrong for saying that.
Эти комнаты - these rooms. "This is/these are" is always это. As discussed above, "these are my rooms" would be "это - мои комнаты".
I also entered that solution, and yes, it is 100% identical in meaning.
Another mnemonic hint for portuguese speakers: remember of the word "Cômodo"
From Latin caminata - a heated room
Can we say: these are my rooms?
It would rather be Это мои комнаты. But I wouldn't know if your sentence is also acceptable for Эти комнаты - мои. I just feel there is a small difference to take in account, I guess.
What I can recall is that the - means "is/are" but I guess bot phrases are right
I keep hearing "это комнате мое".
I put "theese are my rooms" and it was counted wrong even though it is the same thing.
It is not the same. Yours is the translation to «Это — мои комнаты».
Why мои instead of мне?
Мои: are mine.
Or "to me"
It's to emphasize "мои" - мои, не твои, уходи быстро или я убью тебя.
'These are my rooms' is saying the exact same thing. Stop being nitpicky.
You should at least accept my answer of 'These are my rooms'. It's saying the same damned thing.