4.1 problem 46
4.2 problem 47
4.3 problem 48
4.4 problem 49
4.5 problem 50
4.6 problem 51
4.7 problem 52
4.8 problem 53
4.9 problem 54
4.10 problem 55
4.11 problem 56
4.12 problem 57
4.13 problem 58
4.14 problem 59
4.15 problem 60
4.16 problem 61
4.17 problem 62
4.18 problem 63
4.19 problem 81
4.20 problem 85
4.21 problem 86
4.22 problem 87
4.23 problem 88
4.24 problem 89
4.25 problem 90
4.26 problem 91
4.27 problem 92
4.28 problem 93
4.29 problem 94
4.30 problem 95
4.31 problem 96
4.32 problem 97
4.33 problem 98
4.34 problem 99