[jhallenworld]

Try maxima, it's open source:

https://maxima.sourceforge.io/

I used it when it was called Macsyma running on TOPS-20 (and a PDP-10 / Decsystem-20).

Text interface will require a little learning, but not much.

[jgalt212]

Maxima is amazing and has a GUI. My only beef with it is it doesn't show its work step by step.