remapping my right alt key to act as the left one

Hi, I wonder if anybody could help me?

I would like to remap my right Alt key to work in the same way as the left Alt key. I could use Karabina elements to do this, but annoyingly this seems to break my alt+cmd+eject keyboard shortcut.

Ive found this article on how apple recommends remapping keys, but im not sure how to adapt it for my specific needs - would somebody be able to help possibly?

https://apple.stackexchange.com/questions/283252/how-do-i-remap-a-key-in-macos-sierra-e-g-right-alt-to-right-control

many thanks

Nick