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.

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 (Scenario 1)
or Carol is 3rd and Dana is 5th (Scenario 2). 

"Brenda is not younger than Emily"
This means Brenda must be older than Emily.

"Brenda is not the oldest..."
This means that Adele must be the oldest since we have been told explicitly it's not Brenda or Carol and Dana is younger than Carol and Emily is younger than Brenda. 
In the Scenario 1 above, Brenda is 3rd oldest and Emily is 5th.
In Scenario 2, Brenda is 2nd oldest and Emily is 4th.
In either scenario, Brenda is two years older than Emily.