Answer
Brenda is 27
Reasoning
Carol was born 2 years before Dana and is not the oldest of them all.
This means that Carol is 2nd and Dana is 4th or Carol is 3rd and Dana is 5th.
Brenda is not younger than Emily (meaning B>E) and is not the oldest.
Hence, Adele must be the oldest.
In the first scenario above, Brenda is 3rd and Emily is 5th, in the second Brenda is 2nd and Emily is 4th, either way Brenda is two years older than Emily.