Dax to Power Query

I updated my answer, hope this works for you 

let
    Source = TableName,
    GroupedTable = Table.Group(Source, {"ID"}, {
        {"NewMeasure", each 
            let
                form_id = Table.FirstN(_, 1){0}[ID],
                FilteredTable = Table.SelectRows(Source, each [ID] = form_id and [Answer] = _[Extract_Measure]{0}),
                MaxValue = List.Max(FilteredTable[Extract_Measure])
            in
                MaxValue
        }
    })
in
    GroupedTable