R Markdown script for data processing

We need someone with R Markdown skills. We need a simple .RMD script for the following task.

We have a folder with many .xslx files with arbitrary names. I attach two example files.

Your job is two write a loop that (1) calls each of the files in the folder, (2) make some simple calculations for each file, (3) add a row for each file with calculated variables to a masterfile where information for all files will be saved.

Deadline is 1 day.

Budget is 30 USD.

I only hire freelancers who have understood the task. Thanks!