"Livia, how are you doing?"
Translation:Livia, quomodo tu te habes?
Quid usually means what. In Spanish the how and what are used interchangeably in some cases though. It's a good question. Hopefully someone else has a more thorough explanation for you.
The use of "tu" seems to be overkill here. If the item intends "you" to be emphasized in the Latin answer, the English given should reflect that somehow. (Also, I put Livia at the end of the sentence -- it should not matter where the vocative is placed.)
It is accepted now. It takes a while for new entry changes to be operable on all platforms. (I’m using the Duolingo app on iPhone.)
Habeo = i have Habes = you have Habet = he/she/it has
o = 1st person singular s = 2nd person singular t = 3rd person singular
mus = 1st person plural tis = 2nd person plural nt = 3rd person plural