Goal: Create a real, editable Excel workbook (.xlsx) for my monthly sales records.

Input: the table already in this project, uploaded from monthly-sales-input.csv (24 rows; columns Order_ID, Order_Date, Region, Units, Unit_Price_GBP, Note). Use the data exactly as it is. Do not add, remove or change any rows.

Sheets: exactly three sheets named Orders, Summary and ReadMe.
1. Orders: keep all 24 input rows in their original order with the original columns. Keep Order_ID as four-character text (for example 0001, with its leading zeros). Store Order_Date as real Excel dates shown as yyyy-mm-dd. Add a column Line_Total that is an editable formula, Units x Unit_Price_GBP, on every row (formulas, not pasted values). Keep the zero-unit row and the negative return row.
2. Summary: four totals (September 2026 North, September 2026 South, October 2026 North, October 2026 South) plus a grand total. Every total must be a formula that reads from the Orders sheet (for example SUMIFS on Line_Total by month and region), not a typed number.
3. ReadMe: state that the currency is GBP; that Order_Date is the order date; that the zero-unit row 0008 is a cancelled shipment kept at zero and the negative row 0016 is a return kept as a negative amount; and how to update the workbook (add rows to Orders, copy the Line_Total formula down, and check that the Summary ranges include the new rows).

Formatting: bold header row with a light fill, frozen header row on Orders, readable column widths, and GBP currency format on Unit_Price_GBP, Line_Total and the Summary totals.

Checks: no macros, no external links, no password protection, no charts. When you have built it, check that Orders has 24 data rows and that the Summary grand total equals the sum of the four group totals, and tell me those five numbers.

Output: give me the finished workbook as a downloadable .xlsx file.