Sum datatable values by unique id and add to another column

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just a sample

(From d In YourDatatableVariable.AsEnumerable
Group d By k=d("ID").toString.trim Into grp=Group
Let sm = grp.Sum(Function (x) Convert.ToDouble(x("Value").toString.Replace(",",".").Replace(" ","").Trim)) Let sn = grp.Sum(Function (x) Convert.ToDouble(x("TaxValue").toString.Replace(",",".").Replace(" ","").Trim))
Let sb = grp.Sum(Function (x) Convert.ToDouble(x("Tax").toString.Replace(",",".").Replace(" ","").Trim))
From g In grp
Order By YourDatatableVariable.Rows.IndexOf(g)
Let ra1 = g.ItemArray.Take(2).toArray
Let ra2= new Object(){sm,sn,sb}
Let ra = ra1.Concat(ra2).toArray
Select r = NewDatatableVariable.Rows.Add(ra).CopyToDataTable

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