apt install npm Unable to correct problems, you have held broken packages. code example

Example 1: Unable to correct problems, you have held broken packages.

sudo apt-get install -f
sudo dpkg --configure -a

Example 2: Unable to correct problems, you have held broken packages

$ sudo dpkg --list

then look for a package with the name of the one you're trying to install
eg mysql and purge them by name. I repeat by name. 

$sudo apt-get purge <package name>