i don't know where to start, pretty new in power bi or Dax

CodePudding user response：

Try this code:

AverageOfSubTotal =
AVERAGEX (
    SUMMARIZE ( YourTable, YourTable[PurchaseOrderID], YourTable[ProductCategory] ),
    YourTable[SubTotal]
)

CodePudding user response：

Use this as a new Measure

Avg Subtotal = 
AVERAGEX(
    SUMMARIZE(
        'Table',
        'Table'[PurchaseOrderId],
        'Table'[ProductCategory],
        'Table'[SubTotal]
    ),
    'Table'[SubTotal]
)