2007 book6 and 7

hi, my friend gave me his 2007book6 and 7, i wonder 1. how different will it be from the 2008 version? 2. will anyone have the answer explanation for 2007 book 6 and 7? my friend can’t find his. 3. is it worth to buy 2008 version book 6 and 7? thanks in advance.

20-30% material has been changed and that’s why CFAI has given only 96 questions in their 2006 exam.