Subtracting a PlayerPref Instead of Setting It

How can I subtract a PlayerPref instead of setting it so I want
PlayerPrefs.GetInt("Player Style"); to Subtract 5 instead of doing
PlayerPrefs.SetInt("Player Style", 5); since it wont always equal 5

Help would be much appreciated

 

Or in just one line:

Code (CSharp):

1. PlayerPrefs.SetInt( "Player Style", PlayerPrefs.GetInt("Player Style") - 5 );

 

I would highly recommend using my solution here:
http://forum.unity3d.com/threads/playerprefs-management-system.250572/#post-1656264

It allows you to easily add/subtract playerprefs via Prefs.Lives += 10;

 

Thank you guys!