"How many sons do you both have?"
你们都有几个儿子 should this be a correct answer. Duolingo has always used "you guys" for plural you and whilst I know that both means plural I felt it was trying to get me to the next stage of complexity. I am reporting it as they should either use you guys or accept 都 as part of the answer, mind have i got it in the right place??
Mostly correct. However, "You guys" are informally treated as 你们.
都 is usually exceptional for the translation, even if you want to specify that all responders are assumed to have certain amount of kids. Without 都, the sentence is generic, which can mean
How many sons do (at least some of) you have?
So yes, 都 is used to avoid ambiguity. Yet, since "you" in the English sentence does not specify any numeral and whether or not the subjects are all performing the action, the translation is not unique, which can suggest:
- 你们俩有几个儿子？ (Literal translation of the word "both" as an adverb)
- 你们有几个儿子？(which can possibly exclude some of "you" subjects)
- 你们都有几个儿子？(where 都 includes all subjects)
The suggestion of @NasuSamaruk0 你们俩有几个儿子？is the perfect translation to include "both" in the sentence.
你们都有几个儿子? is not preferable because 都 works with statements, and hence Yes-or-no questions as well.
You all (or both) have two sons.
(Note we don't say this to a couple but 2 or more separate people)
Do you all (or both) have two sons?
If 都 is used in an open question, it would indicate sacarsm or an emotion; By asking such question, you are no longer concern about the actual answer.
Where have you all gone? (You should have been here.)
How long have you been dating each other? Why you still haven't got married? (You should marry now.)
because 几 in 几个 is considered a question character, it would replace 吗, in the same way that using 什么 replaces 吗
多少 is used for when the answer is possibly a large number, in the hundreds