Elements of Statistical Learning: Exercises

Hi folks, i need to learn and answer a few questions of The Elements of Statistical Learning, by Trevor Hastie (available at http://www-stat.stanford.edu/~tibs/ElemStatLearn/ ). Do you know where can i find the complete solutions of it? I've found a few solutions here and there, but none of them had the questions . I need to solve exercises 4.2, 12.1, 5.15, 5.16 of the current edition and some of them are really tough!

If you don't know where we could find the solutions but are willing to help me =D, i'm trying to solve this question:

Item a is ok, it's enough to use some definitions of LDA.
The second item is getting me mad! I'm only able to solve it if i formulate a different definition of Eb, but this will get me into trouble to solve item c.

Thank you very much, guys!