If Else formula in CRM Custom Field

If Else formula in CRM Custom Field

Hi

I have various billing options for customers, eg 50%, 30% etc of total cost. The percentage field is entered by user.

In the invoice, I need to display this text: Billing
${Invoices.Billing Percentage} of Package Total : $XX amount

But if percentage is entered as 100%, then the text should only display "Billing Total"

How should I write my formula?

Thanks