"I write to that one, what is white."
Translation:Arra írok, ami fehér.
The English sentence is gramatically incorrect, I think. It should be: "I write on what is white" or "I write on the one which is white" or "I write on that one, which is white". But the last one is really weird, and would need some additional words in Hungarian to be surely understood that way.
Thanks so much, it makes sense now because you do write on white paper generally because it is white.
Both sentences don't fit together. The Duo answer: Arra ìrok, ami fehér means: I write on what is white (I write on something white) But Duo asked for the translation for: I write to that one, what is white. And that is: Ahoz irok, ami fehér. (But this doesn't make sense) And it was marked wrong.