Install packages on elementary OS with downgrade

Question

I've been grappling with installing some Ubuntu packages with apt-get so I thought I'd post an example for anyone else struggling with Elementary OS. Here libssl or openssl won't install and these are dependencies I need for R packages. I suspect this is because I have added Ubuntu PPA's and updated already.

Note that reinstalling with apt-get remove or apt-get install -f does not resolve this.

Answer 1

This can be resolved by installing aptitude with:

sudo apt-get install aptitude

Then running

sudo aptitude install libssl-dev

and selecting the options as follows.