Efficient way to transform a table

Hi, ngct1112 

I tried it, and I got the final result, but since PowerQuery is not my area of expertise, I did not find a very effective method. Ideally, I should create a custom function to complete it.
Below is my code. You can see that this is not efficient, maybe you have better insights.

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WMjAwjDc0MDBQ0lFyBGIDPVNTIGWoFKuDIucEEtQzMgdSRuhyzmA5YyBpDJcyAhJAAW+wkRaoRkLlfCByFihGQuV8wXKWUDNjAQ==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [ID = _t, User = _t, Cost = _t, Rank = _t]),
#"Changed Type" = Table.TransformColumnTypes(Source,{{"ID", type text}, {"User", type text}, {"Cost", type number}, {"Rank", Int64.Type}}),
#"Grouped Rows" = Table.Group(#"Changed Type", {"ID"}, {{"Content", each _, type table [ID=nullable text, User=nullable text, Cost=nullable number, Rank=nullable number]}}),
//there should be a function
#"Added Custom" = Table.AddColumn(#"Grouped Rows", "User 1", each [Content]{0}[User]),
#"Added Custom1" = Table.AddColumn(#"Added Custom", "Supplier 1 Cost", each [Content]{0}[Cost]),
#"Added Custom2" = Table.AddColumn(#"Added Custom1", "User 2", each [Content]{1}[User]),
#"Added Custom3" = Table.AddColumn(#"Added Custom2", "Supplier 2 Cost", each [Content]{1}[Cost]),
#"Added Custom4" = Table.AddColumn(#"Added Custom3", "User 3", each [Content]{2}[User]),
#"Added Custom5" = Table.AddColumn(#"Added Custom4", "Supplier 3 Cost", each [Content]{2}[Cost]),
// function end
#"Removed Columns" = Table.RemoveColumns(#"Added Custom5",{"Content"})
in
#"Removed Columns"

 By the way, there is a PowerQuery forum here. Perhaps this question can be answered quickly in that forum, and there are many experts in this area. If you can find a better answer, please share it for others to learn, thank you.

Best Regards,
Community Support Team _ Zeon Zheng