How to resolve the errors that show up when trying to install Unity tweak tool?

When I try to install unity tweak tool with

sudo apt-get install unity-tweak-tool

the output is

Reading package lists... Done
Building dependency tree       
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 unity-tweak-tool : Depends: unity-webapps-common but it is not going to be installed
E: Unable to correct problems, you have held broken packages.

I tried Synaptic and Ubuntu software center also. I have Ubuntu 16.04 LTS.

I'm also using Ubuntu 16.04.

Note : If you have tried installing tweak-tool before please visit Removing Unity-Tweak-Tool first and follow all instruction.

Now to install follow below steps:

• First open Terminal (Alt+Ctrl+T) and paste sudo apt-get install unity-tweak-tool gnome-tweak-tool.

• Enter your password.

• Now it will take 1-2 minutes to install.

• After installation is finished, you can launch the Tweak-Tool from terminal by typing unity-tweak-tool, OR launch it via Dash.

Try purging the unity tweak tool and reinstalling it(if above one failed to give you desired result).

• sudo apt-get purge unity-tweak-tool

• sudo apt-get autoremove && sudo apt-get autoclean

• sudo apt-get install unity-webapps-common unity-tweak-tool

• sudo apt-get install unity-tweak-tool

I Hope this time it works for you as it working for me.

Found this article so might help you solve the install. See extract of the 2nd option I believe would help install missing dependencies also:

sudo apt-get install gdebi

wget http://archive.ubuntu.com/ubuntu/pool/universe/u/unity-tweak-tool/unity-tweak-tool_0.0.7ubuntu2_all.deb

sudo gdebi unity-tweak-tool_0.0.7ubuntu2_all.deb

unity-tweak-tool

I'm using Ubuntu 18.04, it's March 2019 and I've just installed unity-tweak-tool through the terminal this way:

On Ubuntu, open "Software & Updates" screen. Search for it in your dash.

Check The first 4 options, as on the screenshot:

It will ask to do a update when you save. Allow it.

Open your terminal and install normally: sudo apt-get install unity-tweak-tool

PS: Kudos to this answer.