Following the instructions for "For Precise [Ubuntu 12.04] LTS (v3.5.13.1)" from:
http://www.trinitydesktop.org/wiki/bin/view/Documentation/UbuntuBinaryInstal....
I got these "Failed to fetch" messages with "apt-get update":
From: http://ppa.quickbuild.pearsoncomputing.net/trinity/trinity-v3.5.13/ubuntu/di...
source/Sources binary-amd64/Packages binary-i386/Packages
Error: 404 Not Found
From: http://ppa.quickbuild.pearsoncomputing.net/trinity/trinity-builddeps-v3.5.13...
/source/Sources /binary-amd64/Packages /binary-i386/Packages
Error: 404 Not Found
I assume this is why I got so many "unmet dependencies" when I tried "apt-get install"
<snip>
Why are you attempting to use Quantal repositories? Check your /etc/apt/sources.list file and ensure that "precise", not "quantal", is part of the four TDE lines.
Tim