How to pin Firefox to the previous version on Linux Mint

There are occasion where you may want Linux Mint to pin a specific version of firefox on Linux Mint, you can do the following:

# vim /etc/apt/preferences

Package: firefox
Pin: 3.0*
Pin-Priority: 800

1. "Package" refers to the name of the package
2. "Pin" refer to the criteria used for the pinning. In this case version 3.0 of firefox
3. "Pin-Priority": Priority to handle multiple pin entries

To get back your old programs, do the following:

apt-get upgrade 
OR
apt-get update