80.6 Chapter IV. Methods of solution: First order equations. section 33. Problems at page 91

80.6.1 problem 1
80.6.2 problem 2 (eq 39)
80.6.3 problem 3 (eq 41)
80.6.4 problem 4 (eq 50)
80.6.5 problem 8 (eq 68)
80.6.6 problem 8 (eq 69)
80.6.7 problem 9 (a)
80.6.8 problem 9 (b)
80.6.9 problem 9 (c)
80.6.10 problem 9 (d)
80.6.11 problem 9 (e)
80.6.12 problem 10 (a)
80.6.13 problem 10 (b)
80.6.14 problem 10 (c)