5.1 problem 1
  5.2 problem 2
  5.3 problem 3
  5.4 problem 4
  5.5 problem 5
  5.6 problem 6
  5.7 problem 7
  5.8 problem 8
  5.9 problem 9
  5.10 problem 10
  5.11 problem 11
  5.12 problem 12
  5.13 problem 13
  5.14 problem 14
  5.15 problem 19
  5.16 problem 21
  5.17 problem 22
  5.18 problem 25
  5.19 problem 26
  5.20 problem 27
  5.21 problem 28
  5.22 problem 29
  5.23 problem 30
  5.24 problem 30
  5.25 problem 32