$ sudo apt-get update
$ sudo apt-get install libkdecore5 

libkdecore5 is installed in your system.

Make ensure the libkdecore5 package were installed using the commands given below,

$ sudo dpkg-query -l | grep libkdecore5 *

You will get with libkdecore5 package name, version, architecture and description in a table

libkdecore5 package basic information: