Formula to add a date to another date

I am trying to add a date to anotehr date to get a new date column based on the previous dates. It’s to create a list of tasks that need to be done a certain number of days apart from each other (100 tasks) that will be used reguarly.

I have a date column. I need another column that adds 84 days to the other column. How do I do this? I’ve done a good amount of trying to figure it out using google and formula support info but can’t figure out a way I could do it.