Excel Billing Sheet Setup

I’m looking for a clean, easy-to-maintain billing spreadsheet built in Excel (or Google Sheets if you prefer). The sheet will be used to log transactions and generate simple invoices, so I only need basic calculations—SUM, AVERAGE, and straightforward line-item totals. No macros or pivots required.

What I’d like delivered:
• One tab for raw data: client name, item/service, quantity, rate, tax/discount, and payment status.
• Automatic subtotal, tax, and grand-total fields driven by standard formulas.
• A second, print-ready invoice layout that pulls from the data tab and shows sequential invoice numbers I can update manually.
• Formulas protected from accidental edits, with the option for me to add or delete rows without breaking anything.
• A brief one-page guide explaining where to enter data, how the totals work, and how to duplicate the invoice for new clients.

Please share an example or screenshot of a similar sheet you’ve created and let me know how soon you can hand over the finished .xlsx file. I’ll review quickly and provide prompt feedback so we can wrap this up without delays.