Some are assuming she is affiliated with Brazil - standing next to the Brazilian President, if so, she’s 17.
http://www.unicef.org/media/media_50192.html
The two female J8 Delegates from Brazil are 16 & 15 years old and the one in the photo looks like the 16 year old...Mayara Tavares
http://www.j8summit.com/files/j8%202009%20biographies.pdf