Translation:There is a post office near my house.
Does it make sense to assume they are talking about "my house"? You could argue the context lends itself better to "my", but "the house" seems perfectly valid.
I think that いえ used without any other specification indicates your own house?
Put in "close to my house" instead of "close by my house". Is there a difference?
I am from the US and "close by" is an awkward phrase I never hear. I guess it's technically correct, but nobody says it. It's always "close to" in this case. The two phrases mean the exact same thing, in my experience, so I have no clue why your answer was rejected.
Close to.. Close by.. Near to.. Nearby.. All are correct.. Just duo doesnt seem aware of this?
because post office is the subject of arimasu, therefore post office is the subject of "there is a..."
I put my house is close to the post office, and it counted my answer as wrong.
I guess my question is since they are close together does it really matter which one i say is near the other?
Yes, it matters, because "There is a post office near my house" and "My house is close to the post office" are different grammatical constructions.
Note that it doesn't say "The post office is close to my house", which would indeed be more or less interchangeable with your version, but uses "There is (...)" instead. The Japanese sentence literally translates to "In the vicinity of my house, there is a post office", which is different from "My house is (...)", regardless of whether you switch 'house' and 'post office'.
If I say 'There is a post office near home.', surely it's implied that it's 'my home'.
I understood now that いえのちかくに means "House's nearby" and chikai turned into chikaku because chikai is used to describe the existence of something? (Like suyoku fukimasu "blows strongly").
My house and my place are the same in English. Don't put them both as answers