Is it possible to add to a value within a set modifier?

[#1]

I apologize if this has already been answered. 

I have the following expression that I would like to use. However instead of doing a union between "EFFECTIVE_DATE" and "(1/24)" I would like to add the value of 1/24 to the value of "EFFECTIVE_DATE"  Is this possible within a set modifier? If so I would greatly appreciate any help or any possible work arounds.

FirstSortedValue

({<Bus_Begin_Date={"=Timestamp(EFFECTIVE_DATE+(1/24))"}>}Bus_Price,Bus_Begin_Date)