Here is a simple function you can use if you need your PHP application to display a tentative delivery/completion date to your customer. It excludes the weekends in calculation so only business days are considered. For example, if your e-commerce site ships a product in three business days and customer orders on Thursday then this function will return tentative delivery day as Tuesday, not Sunday.
A few days back I was driving my five year old son to school because we missed his school bus. Normally when this happens, we catch the bus from one of the next few picking points within our locality but this time we were so late that we had no option other than driving all the way to school.