Zanzibar is also known as Unguja
Would "shuka bandarini ya Zanzibar" be wrong? If so, why?
The 'clue' for 'at' indicates kwenye, but it's not included in the answer. Why is that so?
The hints give the meaning(s) of a word or phrase. It is not necessarily giving you the answer.
Please stop putting "Kwenye" in the hints on the sentences you don't want us to use it in! Have already missed three this lesson precisely for this reason.