Brief explanation of design and assumptions: This is a solution of Problem 2, Sales Tax. I worte it in Ruby and used Rspec and Rake for automated testing. To give intputs, there is input.txt file exist in the folder. Assumptions to test solution? 1- $ cd sales_tax 2- Paste input into the input.txt file ( one by one) 3- Check output from the command line by running the command: $ ruby sales_tax.rb 4- To ensure rspec tests are working use: $ rake 5- To check it online, use this link: http://rubyfiddle.com/riddles/48fce/7