1) make sure /etc/apt/sources.list has bionic-updates enabled for universe (and multiverse?)
2) sudo apt update
3) sudo apt install nodejs-dev libssl-dev
...
The following packages have unmet dependencies:
nodejs-dev : Depends: libssl1.0-dev (>= 1.0.2) but it is not going to be installed
E: Unable to correct problems, you have held broken packages.
In other words, the current nodejs-dev does not fit into the Ubuntu 18.04 ecosystem.
Here's a short way to see the failure:
1) make sure /etc/apt/ sources. list has bionic-updates enabled for universe (and multiverse?)
2) sudo apt update
3) sudo apt install nodejs-dev libssl-dev
...
The following packages have unmet dependencies:
nodejs-dev : Depends: libssl1.0-dev (>= 1.0.2) but it is not going to be installed
E: Unable to correct problems, you have held broken packages.
In other words, the current nodejs-dev does not fit into the Ubuntu 18.04 ecosystem.