(2) Adding polynomials with multiple variables
(3) Subtracting Polynomials
(4) Subtracting Polynomials with multiple variables
(5) Adding and Subtracting Polynomials - very good video
►Interactive lessons -- may be best to do after viewing the videos here.
Click Unit 5, Lesson 22, Play Lesson, Adding and Subtracting.
You may read along with the lesson in the left sidebar.
Note: Lesson does not seem to work in Safari browser.