Replacing values with data calculations

Hi 350z, as lbendlin mentioned - for future requests provide sample data in usable format (not as screenshot) and expected result based on sample data. I haven't prepared exactly what you asked for, but check this - it is better for further analysis:

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("1VFNC8IwDP0rYSAoaElbrdtR1MlgThE9jR0mm16GA53+frO24kfFu9A26evLa3hJUy9dbFa7dZQsMkBEGEAYQxjN45nX9z5X1k8dzMJxvq/PMK2LkpCwLBuITpcmr6qygG6nR+A6PzcXB93WdAVd0D00vS/FBjU8reFq6Q58Tg/JtaqegQ8DJgJKfGRqTHEk6ZDc8IXDF8iwVbGhJVuu72ojsdBo6ziiPXxY1JJgcju+p0IFTLZcrmxDSv+jfjn7MiCuB4QclpMo+bv5uH5Ln0lh/EbrN/528HtFdgc=", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Column1 = _t, Column2 = _t, Column3 = _t, Column4 = _t, Column5 = _t, Column6 = _t, Column7 = _t]),
    TrimmedTextColumn1 = Table.TransformColumns(Source,{{"Column1", Text.Trim, type text}}),
    Ad_Grouping = Table.AddColumn(TrimmedTextColumn1, "Grouping", each if Text.StartsWith([Column1], "[Grouping", Comparer.OrdinalIgnoreCase) then [Column1] else null, type text),
    FilledDownGrouping = Table.FillDown(Ad_Grouping,{"Grouping"}),
    RemovedTopRows = Table.Skip(FilledDownGrouping, each [Column1] <> "Labor Code"),
    PromotedHeaders = Table.PromoteHeaders(RemovedTopRows, [PromoteAllScalars=true]),
    RenamedColumnGrouping = Table.RenameColumns(PromotedHeaders,{{List.Select(Table.ColumnNames(PromotedHeaders), (x)=> Text.Contains(x, "[Grouping]",Comparer.OrdinalIgnoreCase)){0}?, "Grouping"}}),
    ReplaceValues = Table.TransformColumns(RenamedColumnGrouping, {}, each if List.Contains({"Null", ""}, _) then null else _),
    ChangedType = Table.TransformColumnTypes(ReplaceValues, List.Transform(List.RemoveItems(Table.ColumnNames(ReplaceValues), {"Grouping"}) , (colName)=> {colName, type number}) & {{"Grouping", type text}}, "en-US"),
    RemovedErrorsLaborCode = Table.RemoveRowsWithErrors(ChangedType, {"Labor Code"}),
    FilteredRowsLaborCode = Table.SelectRows(RemovedErrorsLaborCode, each ([Labor Code] <> null)),
    ReplaceFeetInstalledPercent = Table.ReplaceValue(FilteredRowsLaborCode, 
        each [#"Feet Installed (%)"],
        each [#"Feet Installed (ft)"] / [#"Total Feet (ft)"],
        (x,y,z) => if y = null then z else x,
        {"Feet Installed (%)"} ),
    ReplacePartsInstalledPercent = Table.ReplaceValue(ReplaceFeetInstalledPercent, 
        each [#"Parts Installed (%)"],
        each [Parts Installed] / [Total Parts],
        (x,y,z) => if y = null then z else x,
        {"Parts Installed (%)"} ),
    GroupedRows = Table.Group(ReplacePartsInstalledPercent, {"Grouping"}, {{"All", each _, type table }, {"Feet Installed (%) Avg per Group", each List.Average([#"Feet Installed (%)"]), Percentage.Type}, {"Parts Installed (%) Avg per Group", each List.Average([#"Parts Installed (%)"]), Percentage.Type}}),
    ExpandedAll = Table.ExpandTableColumn(GroupedRows, "All", List.RemoveItems(Table.ColumnNames(ReplacePartsInstalledPercent), {"Grouping"})),
    ChangedType2 = Table.TransformColumnTypes(ExpandedAll,{{"Labor Code", Int64.Type}, {"Feet Installed (%)", Percentage.Type}, {"Parts Installed (%)", Percentage.Type}, {"Total Feet (ft)", type number}, {"Feet Installed (ft)", type number}, {"Total Parts", Int64.Type}, {"Parts Installed", Int64.Type}})
in
    ChangedType2