This document discusses rational expressions and how to add and subtract them. It defines a rational expression as the ratio of two polynomials that can be written as p/q. It provides examples of adding and subtracting fractions with the same and different denominators. It then lists the steps for adding and subtracting rational expressions, which include factoring if necessary, canceling common factors, finding the lowest common denominator (LCD), and adding or subtracting the numerators and placing the result over the common denominator. The document provides examples worked through each step to demonstrate how to add and subtract rational expressions.