"They eat your food."
Translation:De äter din mat.
When translating ENG SWE, it's ambiguous as to whether the you is singular or plural. Thus both din/ditt/dina and er/ert/era will be accepted throughout the course. (And if it isn't, please use the report function to make us aware.)
As for when to use either, the rules are:
- En-word: din / er
- Ett word: ditt / ert
- All plurals: dina / era
No, no, barnet is "the child" and barnen is "the children". This is because barn follows the most basic pattern of ett-words that are the same in the singular indefinite as in the plural indefinite.
There are some great tendencies in this thread by Zzzz....: https://forum.duolingo.com/comment/6329293
And you may also find this thread useful: https://forum.duolingo.com/comment/26420394