trouble installing packages

[DeepThought]

These ppa's don't exist. The darklin20 ppa stopped at ubuntu vivid, there is no xenial ppa.
the mc3man ppa is for ubuntu trusty, the xenial ppa is a different url.

Code:

W: The repository 'http://ppa.launchpad.net/darklin20/bomi/ubuntu xenial Release' does not have a Release file.
W: The repository 'http://ppa.launchpad.net/mc3man/trusty-media/ubuntu xenial Release' does not have a Release file.

I suggest you remove them using:

Code:

file:///usr/share/doc/litemanual/software.html#pparem

and then try updating.