Windows Form App - Business Days/Hours

Hello all,

I'm trying to create an application which will allow my collegues to calculate their remaining holidays based on the remaining hours left on their ticker. Here's the main idea:

I would like to provide the collegues with an app that when they enter eg. 91h:12m in a textbox, it shows the equivalent in full days (business days, knowing that a full working day is 7h:36m and not 24h) and in half days (business days, knowing that a half business day is 3h:48m and not 12h). So for this example (91h:12m) it should show 12 business days and 24 half business days.

Also backwards, when they enter 3 days in a second textbox, it will show how many business hours it represents.

I have worked with DateTime objects before but I have no clue how to get started with this...

Best regards,

Kevin