Explanation:
To be a proper fraction the numerator (top number) must be less the the denominator (bottom number). Let’s start at the top.
27/27
This would be an improper fraction because the numerator is equal to the denominator, not less.
6/17
Because 6 is less then 17 this would make it a proper fraction
8/9
Same case as the last one, this is a proper fraction because the numerator is less then the denominator
21/5
21 is definitely more the 5 making this a improper fraction.
Hope this helped :)