I have a file in which I don't know how to open..

[The Riddler]

Hey guys, this is my first thread. I was wondering if anyone on the forum could tell me how to open a .app.dmg extension because when I double click the file, nothing happens.
I'm using a 13' Macbook Pro 2011 if that is any help.
Thanks a lot guys!

 

[balamw]

What happens when you open a plain .dmg file? You should see it mount in Finder.

B