How to implement rule into BPM Approval rules for Expenses?

Summary:

Content (please ensure you mask any confidential information):

Hi All,

I found this clause below:

Expense Report.Expense Report Total*CurrencyConversion.getRate(Expense Report.Reimbursement Currency,"USD",Expense Report.Expense Report Date,"Corporate",0)

In order to convert Expense Reports of different currencies to one currency in order so that they can all go through Approval Rules in the same way.

How do I input this above statement into BPM? Could somebody help with this please, if a screenshot is possible?

Thanks in advance!

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

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