let
Source = Excel.CurrentWorkbook(){[Name="Table1"]}[Content],
#"Changed Type" = Table.TransformColumnTypes(Source,{{"Column1", type text}, {"Column2", Int64.Type}, {"Column3", Int64.Type}}),
#"Added Custom" = Table.AddColumn(#"Changed Type", "Custom", each [Column3] * -1),
#"Removed Columns" = Table.RemoveColumns(#"Added Custom",{"Column3"}),
#"Renamed Columns" = Table.RenameColumns(#"Removed Columns",{{"Custom", "Column3"}}),
#"Appended Query" = Table.Combine({#"Renamed Columns", Table2}),
#"Grouped Rows" = Table.Group(#"Appended Query", {"Column2"}, {{"Total", each List.Sum([Column3]), type number}})
in
#"Grouped Rows"