Hi Francisco,
You'll have to extract the Start Date and End Date by creating variables
v_StartDate = Userresponse("<Enter Start Date (or whatever prompt text you see)>")
v_EndDate = Userresponse("<Enter End Date (or whatever prompt text you see)>")
And then, use the 1st formula that Chandresh provided by replacing Admit Date and Order Date with what we just created, v_StartDate and v_EndDate to create an object that calculates the difference in seconds. And use the 2nd formula by Chandresh to convert those seconds to days hh:mm:ss.
You'll have to update those 2 formulas by replacing commas with semi-colons, "&" sign with a "+" sign, and obviously the <number of seconds> with the object you created in previous step.
Give it a shot and let us know what happens.
Thanks,
Mahboob Mohammed