This workshop will help you get started using R Markdown to create documents with R code embedded.
The files, which were created with RMarkdown and reveal.js are rmarkdown.Rmd and rmarkdown.html (you need a number of libraries and other supporting files for them to work).
Look at the HTML version for the questions. Download and open the RMarkdown file for the answers.
R Markdown Cheat Sheet also from RStudio
Official R Markdown Documentation and Guide from RStudio
Introduction to R Markdown by Garrett Grolemund is a good overview from RStudio
Creating Dynamic Documents with R Markdown and Knitr by Marian L. Schmidt
R Markdown for writing reproducible scientific papers by Mike Frank & Chris Hartgerink
R Markdown from Penn State Stat 485: video tutorials on R Markdown
R for Data Science: R Markdown: chapter in the R for Data Science book
Reproducible Research Using R Markdown and Git through RStudio by Marian L. Schmidt
R Markdown magic is made possible by knitr from Yihui Xie