Challenge
https://ampscript30.com/ampscript-challenge-day5/
To offer different discounts depending on customers’ upcoming birthdays.
Solution
Hello %%=ProperCase(FirstName)=%%,
To celebrate your birthday, we are offering you a special discount!
%%[
SET @now = FormatDate(NOW(), 'MM/dd')
SET @birthdate = FormatDate(Birthdate, 'MM/dd')
SET @difference = DateDiff(@now, @birthdate, 'D')
IF @difference <= 7 AND @difference > 0 THEN
SET @discount = '15%'
ELSEIF @difference > 7 AND @difference <= 14 THEN
SET @discount = '10%'
ELSE
SET @discount = '5%'
ENDIF
]%%
You will receive a %%=v(@discount)=%% discount on your next purchase.

Preview

Summary
There are different ways to achieve the goal depending on how the dates are manipulated.