Here is a solution:
1. Join the data with itself as shown below. The join calculation you see on the left derives the Week LY. So, the data you get from the sheet on the right is the sales for LY.
2. Create the following calculated fields:
3. You can use the Week TY - Date as a filter and display the data as given below.
Hope this helps. A 10.5 workbook is attached.
Weekly Sales.twbx 122.9 KB