Store SUM from table 1 in table 2

Please try this.....

let
	Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WcjQ0MlbSUTI0ABGmQMIIzLIAEWYgrlKsTrSSE1GqnIlS5UKUKlfCqmIB", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type text) meta [Serialized.Text = true]) in type table [#"Part Number" = _t, #"Current Stock" = _t, #"Week 1 Closing stock" = _t, #"Week 2 Closing stock" = _t, #"Week 3 Closing stock" = _t, #"Week 4 Closing stock" = _t, #"Week 5 Closing stock" = _t]),
	#"Removed Columns" = Table.RemoveColumns(Source,{"Week 5 Closing stock"}),
	#"Changed Type" = Table.TransformColumnTypes(#"Removed Columns",{{"Current Stock", Int64.Type}, {"Week 1 Closing stock", Int64.Type}, {"Week 2 Closing stock", Int64.Type}, {"Week 3 Closing stock", Int64.Type}, {"Week 4 Closing stock", Int64.Type}}),
	#"Removed Columns1" = Table.RemoveColumns(#"Changed Type",{"Part Number", "Current Stock"}),
	#"Demoted Headers" = Table.DemoteHeaders(#"Removed Columns1"),
	#"Changed Type1" = Table.TransformColumnTypes(#"Demoted Headers",{{"Column1", type any}, {"Column2", type any}, {"Column3", type any}, {"Column4", type any}}),
	#"Transposed Table" = Table.Transpose(#"Changed Type1"),
	#"Added Custom" = Table.AddColumn(#"Transposed Table", "Total Closing Stock", each [Column2]+[Column3]+[Column4]+[Column5]+[Column6]),
	#"Removed Columns2" = Table.RemoveColumns(#"Added Custom",{"Column2", "Column3", "Column4", "Column5", "Column6"}),
	#"Inserted Text Before Delimiter" = Table.AddColumn(#"Removed Columns2", "Text Before Delimiter", each Text.BeforeDelimiter([Column1], " ", 1), type text),
	#"Reordered Columns" = Table.ReorderColumns(#"Inserted Text Before Delimiter",{"Column1", "Text Before Delimiter", "Total Closing Stock"}),
	#"Removed Columns3" = Table.RemoveColumns(#"Reordered Columns",{"Column1"}),
	#"Renamed Columns" = Table.RenameColumns(#"Removed Columns3",{{"Text Before Delimiter", "Weeks"}})
in
	#"Renamed Columns"