EDITED to update the problem:
I am using some automation rules documented on this site to update my Epic value for {{worklog.timeSpent}}.
It DID NOT work as shown in several submissions in my Cloud environment.
The accepted answer is actually to get the rules to work to update the Epic Values.
I will open a new question about calculating my "% Complete" custom field, if I have additional questions related to that.
BELOW IS NO LONGER RELEVANT TO THIS QUESTION.
Since that worked, I am now trying to update another field (custom field that I created) called "% Complete". I realize that there is a % done field, but it uses tasks completed instead of time.
Anyway, I am not getting the syntax correct on the math. Can someone help me with the syntax?
{{#=}} ( {{worklog.timeSpent}} * 100 ) /
( {{timetracking.originalestimate}} - {{worklog.timeSpent}} ) {{/}}