75.8 Chapter VII. Ordinary differential equations in two dependent variables. Exercises at page 86

75.8.1 problem 8
75.8.2 problem 9
75.8.3 problem 10
75.8.4 problem 11
75.8.5 problem 12
75.8.6 problem 13
75.8.7 problem 14
75.8.8 problem 15
75.8.9 problem 16
75.8.10 problem 17
75.8.11 problem 18
75.8.12 problem 19