Many people in the U.S. confuse business days and work days, but they are not the same. A “business day” is defined as a weekday, while a work day is any working day—Monday through Friday, or Saturday through Sunday. Working on Saturday when you usually don’t is an example of working on a “work day.” If you went to school Monday-Friday during the weekdays and worked Mondays-Fridays for 10 hours and Saturdays for 10 hours, that would be 40 hours of work this week, which would then mean that every Friday night (because Fridays are traditionally weekends) you will have only worked 4 out of 7 days this week—which means that your schedule was 60% business days