Comment 3 for bug 1491978

This isn't a bug, nor a problem with the package.

Something else is listening on port 80, and therefore you can't start nginx. (It by default binds to port 80).

Whatever the other process is (possibly Apache), you should shut it off, run the installation (or apt-get install -f), and then mess with configuration files so things aren't all trying to listen on port 80 at once.