Aggregate Functions in LinQ

' CONSULTA QUE UTILIZA FUNCIONES AGREGADAS
        Dim tblinvoices As List(Of Invoice) = InvoiceDB.GetInvoices
        Dim tbllinq = Aggregate invoice In tblinvoices
                      Where invoice.InvoiceDate > #1/1/2010#
                      Into Average(invoice.InvoiceTotal),
                      Sum(invoice.InvoiceTotal)

        'MsgBox("Promedio = " & tbllinq.Average & "; Suma = " & tbllinq.Sum)
        MsgBox(tbllinq.ToString())