7.1 problem 1 (a)
  7.2 problem 1 (b)
  7.3 problem 1 (c)
  7.4 problem 1 (d)
  7.5 problem 2
  7.6 problem 3
  7.7 problem 4
  7.8 problem 5
  7.9 problem 6
  7.10 problem 16 (a)
  7.11 problem 16 (b)
  7.12 problem 16 (c)
  7.13 problem 16 (d)
  7.14 problem 17
  7.15 problem 18
  7.16 problem 19
  7.17 problem 20
  7.18 problem 21
  7.19 problem 22
  7.20 problem 25
  7.21 problem 26
  7.22 problem 27
  7.23 problem 28
  7.24 problem 29
  7.25 problem 30