This document provides guidance on how to add and subtract polynomials by working through examples of adding and subtracting terms with variables like x, y, and a. It shows how to group like terms, write polynomials in column form, and change subtraction to addition of the opposite term in order to combine polynomials. The examples calculate the sum or difference of polynomials like (4x^2 - 2xy + 3y^2) + (-3x^2 - xy + 2y^2).