PHP / MYSQL Calculation and Update Script

Please see full brief attached for full details:

In short I need s script that can be ran by clicking a button and doing a search query based on the results it then needs to do some simple calculations and then update a column in the table for each record based on the search.

Full details in PDF brief.

There is no admin, or database structure to build or any content input interface etc it is simply creating a script that can run by clicking on a button.