Linux Shout published a tutorial about installing Rstudio and R-base on Ubuntu 20.04 LTS.
How to install Rstudio & R-base Ubuntu 20.04 LTS Linux
Easy commands to install R-base and Rstudio on Ubuntu 20.04 or 18.04 LTS Linux system for R programming language development platform.
How to install Rstudio & R-base Ubuntu 20.04 LTS Linux - Linux Shout