$ sudo apt-get update
$ sudo apt-get install firebird2.5-superclassic 

firebird2.5-superclassic is installed in your system.

Make ensure the firebird2.5-superclassic package were installed using the commands given below,

$ sudo dpkg-query -l | grep firebird2.5-superclassic *

You will get with firebird2.5-superclassic package name, version, architecture and description in a table

firebird2.5-superclassic package basic information: