This document provides an example of how to use a system of linear equations to solve a word problem about book and pencil prices. It contains the following steps: 1) The word problem is translated into a mathematical model with variables (x for book price, y for pencil price) and equations relating the variables. 2) The system of two equations is set up and solved using either elimination or substitution methods to find the values of x and y. 3) The values are substituted back into the original equations to find the total price of 4 books and 2 pencils.