I am working with dates, and I am wondering if there is a standard
formula that I can enter. What I am looking to do is have 4
horizontal rows take one formula and one block on the horizontal line
to take another. (The four I want to add 90 days to the date and the
one I want to add 270). Please help!!!

It's helpful to realize that Excel stores a date internally as an integer
(starting 1/1/1900).

So to do what you want, just add 90 or 270 or whatever, then format the
result as a date.