Answer from cs61c-al (Phillip Chin 16156822) for Question 1
c5 = g4 + (p4 . g3) + (p4 . p3 . g2) + (p4. p3 . p2 . g1)   + (p4. p3 . p2 . p1. g0) + (p4. p3. p2. p1. p0 . c0)