71.19 Chapter 10. Applications of Systems of Equations. Exercises 10.2 page 432

71.19.1 problem 1
71.19.2 problem 2
71.19.3 problem 3
71.19.4 problem 4
71.19.5 problem 5
71.19.6 problem 6
71.19.7 problem 7
71.19.8 problem 8