I can't seem to get this substring extraction to work right. In a normal extraction you can use a variable for the number you're extracting from:
Where 4 would be the desired number extracted. I run into my problem when trying to repace "3" and "1" with variables:
I can get them all to display their respective values by playing with parentheses, but the expression is never able to set X=4 as desired.
My question is: How do you set proper variables within a variable substring extraction.