$ sudo apt-get update
$ sudo apt-get install qtdeclarative5-unity-notificat

qtdeclarative5-unity-notificat is installed in your system.

Make ensure the qtdeclarative5-unity-notificat package were installed using the commands given below,

$ sudo dpkg-query -l | grep qtdeclarative5-unity-notificat*

You will get with qtdeclarative5-unity-notificat package name, version, architecture and description in a table

qtdeclarative5-unity-notificat package basic information: