Google Apps has an easy built-in web Form tool that stores submitted results in a spreadsheet. This is good, but let's make it better.
Introducing Forms with Workflow!
Thanks to Google Apps Scripts, a workflow can begin once the form's submit button is clicked. The most efficient way to demonstrate this is through a video. Play the video to see how it works. Tip: Expand the video to full screen by first clicking "play", and then clicking the full screen symbol at the lower right.
As the video demonstrated when the submit button was clicked, a script composed emails with approve and decline form fields, managed the workflow process, and updated the form's spreadsheet.
Behind the scenes are Google Apps Scripts that begin the workflow, handle declines, and approves. The scripts even prevent email recipients to answer more than once by looking up the statuses in the form's spreadsheet.