Ok., comic book science! How do I love it!
In terms of physique - about 19-24
In terms of mentality - about 5-10
As for intelligence it's harder to say, because, honestly, I don't think intelligence can be attributed to age as much precise as mental state. I personally know a very smart, witty and intelligent ten year old and a certain sixteen year old wich is... oh, God, I still have some sympathy for her, so let's say
brainwashed. But you know the deal
.
And also notice how Einstein was a genious but often acted like a child and how Tesla went nuts, so mentality is also a subject of discussion.
But her (Scarlet's) real age, methinks, is no more than 10 y.o., physique and intelligence artifactially boosted.
Ok., end of comic book science!