How to extract some data from POST API response message vb.net?

this is my code

Private Function POSTData(ByVal json As Object) As Boolean
    Dim url = "***********"
    Dim _httpClient = New HttpClient()
    '_httpClient.DefaultRequestHeaders.Authorization = New AuthenticationHeaderValue("2022080799", "Emt@9674")
    _httpClient.DefaultRequestHeaders.Add("Username", "****")
    _httpClient.DefaultRequestHeaders.Add("Password", "*****")

    Using content = New StringContent(json, System.Text.Encoding.UTF8, "application/json")
        Dim result As HttpResponseMessage = _httpClient.PostAsync(url, content).Result
        Debug.Print(json)
        'Debug.Print(content.ToString)
        If result.StatusCode = System.Net.HttpStatusCode.Created Then
            Console.WriteLine(result.StatusCode)
            Return True
        End If

        Dim returnValue As String = result.Content.ReadAsStringAsync().Result
        If result.StatusCode <> 200 Then
            Throw New Exception($"Failed to POST data: ({result.StatusCode}): {returnValue}")
        Else
            Debug.Print(returnValue)
        End If

    End Using

when I receive the result as follwoing :

"{""status"":200,""message"":""Operation Done Successfully"",""data"":{""billNumber"":""0007"",""sadadNumber"":""2208800110""}}"

how to extract ( "sadadNumber"":""2208800110"" ) ?