Has anyone picked up on the fact that the first world in the sentence is capitalized? That's correct, but it's also a give away too
Is obydwa okay?
no. for feminine nouns (and female people) it's obie or obydwie
oba/obydwa is for masculine not personal and neuter
obaj/obydwaj is for masculine personal
oboje and obydwoje is for two people one male, one female,
I wrote "obydwie kobiety piją herbatę" but it was not accepted.
And it should have been, added now.
I tried now to add the 'longer' forms in all exercices for 'both', but there's a possibility that there's still something which I missed.
I don't understand the forms of 'oba', 'obie' etc. Is there a list of conjugations somewhere please?
My comment here: https://www.duolingo.com/comment/19529552$comment_id=19554885 has the explanations and links to declension tables.