Hi folks, I am running into the same issue as there is no Ubuntu 18.04 LTS in Cloud Servers section shown in lesson "Setting Up Your Cluster".
And most probably, I can not download kubelet package because I have used "Ubuntu 14 trusty tahr TLs" instead to create my Ubuntu server.
(The following packages have unmet dependencies:
kubelet : Depends: init-system-helpers (>= 1.18~) but 1.14ubuntu1 is to be installed
E: Unable to correct problems, you have held broken packages.
Your help will be greatly appreciated.