$ sudo apt-get update
$ sudo apt-get install libkdesu5 

libkdesu5 is installed in your system.

Make ensure the libkdesu5 package were installed using the commands given below,

$ sudo dpkg-query -l | grep libkdesu5 *

You will get with libkdesu5 package name, version, architecture and description in a table

libkdesu5 package basic information: