"Ili demandas, kaj ni respondas."
Translation:They ask, and we answer.
"peti" is more general. "demandi" is asking a question.
You could put it as: "demandi" = "peti respondon"
"peti ion" = to ask for something
"demandi ion" = to ask for an answer for something
Or another way of putting is is that "peti" is to make a request (same root as "petition"), while "demandi" is to ask a question.
Like what Megan said, peti comes from the same root as petition. So when you see peti, remember petition.
"Ili demandas".... My English is getting in the way of learning this language! xD
As I understand it, answer is a subset of respond. You can respond to something and not actually have the answer. "we answer" means that the problem is solved, but "we respond" means that it's possible that their response didn't actually contain an answer. For all I know, they responded "I don't know".
According to Lernu's vortaro: respondi (respond·i) - to answer, to reply, to respond
"Answer" and "respond" should be interchangeable here. If it isn't accepted, report it.
In this case, respondi and to respond are false friends. They look like they should mean the same thing but have different meanings in the two languages
Let me try to see if there is a better reason, but sometimes in language you just have to shrug and just go along with it