Question 632268
For additional explanation on this topic, please see my own website.  Look for the easy-to-remember and easy-to-spell link www.mathinlivingcolor.com.  At the bottom of this page is a link that takes you to my Homepage.  Near the top of the Homepage, look for the link "Basic, Intermediate, and College Algebra:  One Step at a Time."  Choose Basic Algebra, look in Chapter 4 for Section 4.08 Applications of Systems of Equations.  Several examples are solved IN COLOR, which you should find helpful.  


If you like the website, please recommend it to your friends and family. 


Dr. Robert J. Rapalje, Retired
Seminole State College of Florida