Board Thread:Support Requests - Getting Technical/@comment-25251896-20160225043019

How can I create an expression using #expr (or something similar) in a template where it'll take a previously declared template parameter to solve an expression and output the result?

For example, I have a template that contains the following: Start Date: End Date: ((Start Day) - 1)

How can I make it so the End Date is always one day behind? Regarding possible confusion on why I want to achieve something like that, I just want the end day to be one day behind as the month is always ahead. 