This page describes how to extract RAR files with free software.
RAR is a proprietary archive format. RAR files can not be created with free software. Unrar-free can extract these files, but only supports RAR files before 3.0.
Install the unrar-free package:
sudo apt-get install unrar-free
Create a link to allow Archive Manager to use unrar-free:
sudo ln -s /usr/bin/unrar-free /usr/bin/unrar
Right click on the file in Nautilus and select "Extract Here" or double-click to open with Archive Manager.