How do you acess the unit notes when you are on a mobile device?
Either use an internet browser of keep a copy of duome's extract on your device - https://forum.duolingo.com/comment/17638579 (remember to update your copy regularly - we often tweak the notes in response to questions).
ac instead of a? I think I missed a grammar point somewhere.
Apologies we left out that important explanation, it's now in the notes for the unit Numbers. The rule is that 'a' preceding a vowel changes to 'ac'.
The plurals of "buwch" and "dafad" are "buchod" and "defaid". Both are feminine nouns.