Links
[1] https://www.hootsgo.org/?q=node/6275
[2] http://www.algebrahelp.com/lessons/simplifying/multiplesigns/
[3] http://www.algebrahelp.com/lessons/simplifying/combiningliketerms/
[4] http://www.algebrahelp.com/lessons/simplifying/multiplication/
[5] http://www.algebrahelp.com/lessons/simplifying/distribution/
[6] http://www.algebrahelp.com/lessons/simplifying/foilmethod/
[7] http://www.algebrahelp.com/lessons/simplifying/numberexp/
[8] http://www.algebrahelp.com/lessons/simplifying/varexp/
[9] http://www.algebrahelp.com/lessons/simplifying/polyexp/
[10] http://www.algebrahelp.com/lessons/simplifying/oops/