Date calculation excluding weekends

Hi Friends,

Can please let me know, how to exclude the weekends from date value. Please find the my logic below.

If Header.Flag = 'Y' and Header.CheckInDate is blank,then 12/31/2020

If Header.Flag = 'Y' and Header.CheckInDate is not blank, then Header.CheckInDate - 3 working days (exclude weekends)

If Header.Flag <>'Y'then Current Date + 21 business days

Thanks & Regards,

Balamurugan G