If you want to get the WEEKDAY of a given date, just use a new calculated column on your Sharepoint list with a formula like this:
Then use this new calculated column (named DAYOFWEEK in this sample) on your workflow.
Take a look to the use of that formula at >>> WEEKDAY function
Hi Vikas Reddy:
The WEEKDAY formula mentioned in this document refers to the Sharepoint formula that can be used on a Sharepoint calculated column on a Sharepoint list/library
I would recommend starting a new post with details on your scenario. maybe even include screenshots. But you can probably do what you need by using the dateAddDays function and also format them using the formateDate function.