Exercise 3 has both a clean part and a distorted part. In the clean part, you'll primarily be playing dead notes on most your downstrokes, then with your upstrokes you'll be playing the notes normally. Watch out for the quick legato line at the end of bar 14 where you'll be playing sixteenth note triplets.
The distorted part is a bit more variated than the clean part. While it continues the overall 16th note rhythm, the notes that you accent are spaced out quite a bit more. Practice the rhythm slowly until it starts to feel natural. Also, you'll again encounter that quick legato line in bar 18.
Got it down? Then make your way to the next page for the backing track!