25.3 Chapter 4

25.3.1 problem 2
25.3.2 problem 4
25.3.3 problem 5.1
25.3.4 problem 5.2
25.3.5 problem 5.3
25.3.6 problem 5.4
25.3.7 problem 5.4
25.3.8 problem 7.1
25.3.9 problem 7.1