how many elephants does the zoo have? nope, marked wrong

Could somebody please break down this sentence into the individual words translated?

What is the purpose of adding "có" to the beginning of this sentence? Would the sentance work without it?

Why is the word "there" in the sentence ?? How many elephants are in the zoo is wrong ?!

How many elephants in the zoo was marked incorrect.

"How many elephants are at the zoo" is what I wrote and it was correct.