Removing duplicate data

In the query editor, you add an index-column:

Check the new index-column and sort descending:

Edit the formula in the formula bar to this (otherwise the sort-order will not be kept):

Check columns "Date" and "Art", and remove duplicates:

This is the code that you can paste into the advanced editor to follow the steps along:

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("Xc6xDcAgDETRXVyDZINBtCQhSyD2XyPWWXKR5opXnP7exJJZswxKJMy2k04yLsEFfDnX4Aq+nTVYwY9zC27g5dyDO/h1lt+JlZwP", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type text) meta [Serialized.Text = true]) in type table [Date = _t, Sale = _t, Art = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Date", type date}, {"Sale", Int64.Type}, {"Art", type text}}),
    #"Added Index" = Table.AddIndexColumn(#"Changed Type", "Index", 1, 1),
    #"Sorted Rows" = Table.Buffer(Table.Sort(#"Added Index",{{"Index", Order.Descending}})),
    #"Removed Duplicates" = Table.Distinct(#"Sorted Rows", {"Date", "Art"})
in
    #"Removed Duplicates"