How to setup a BPM rule comparing the expense report amount and the attached authorization amount?

Summary:

We need to setup a BPM rule for expense report approval with a condition when the expense report amount is grater than the attached spend authorization, it needs to be routed to specific approver. In BPM we only see the condition for the expense report total amount but not for the spend authorization total amount.

Do you know if this is possible?

Content (required):

Expense report amount

Attached Spend authorization amount

Version (include the version you are using, if applicable):

23B

Code Snippet (add any code snippets that support your topic, if applicable):