Questions & Answers about Begge børn får lige meget juice.
Begge means both when you are talking about two people or things as one group: begge børn = both children.
Danish also has både ... og ..., but that is used to connect two separate items:
- Både Anna og Peter får juice = Both Anna and Peter get juice
In your sentence, begge is the natural choice because børn already gives you one plural noun phrase: both children.
Børn is the irregular plural of barn.
The forms are:
- et barn = a child
- barnet = the child
- børn = children
- børnene = the children
So this is just a plural form you need to learn as a vocabulary item. It does not follow the most regular plural pattern.