Install two versions of gcc gfortran compiler

[linux-aarhus]

@mismaiel

I am a linux/Manjaro newbie

Then you need to familiarize yourself with how LInux works and in the context Manjaro.

• System Maintenance - Manjaro
• [root tip] [How To] Update Manjaro the smart way
• [root tip] [How To] Avoid common pitfalls as developer
• [Need-To-Know] About Manjaro and AUR

As Manjaro is based on Arch and the vast majority of packages is inherited from Arch - you can learn a lot from using the Arch Wiki.