$ sudo apt-get update
$ sudo apt-get install libktexteditor4 

libktexteditor4 is installed in your system.

Make ensure the libktexteditor4 package were installed using the commands given below,

$ sudo dpkg-query -l | grep libktexteditor4 *

You will get with libktexteditor4 package name, version, architecture and description in a table

libktexteditor4 package basic information: