Как вычислить среднее значение элементов последовательности - Visual Basic .NET

If Not IsNothing(BiologyReadyLine) Then BiologyAverageValue = BiologyReadyLine.Average(Function(n) Convert.ToInt32(n.ToString))

Public Class Form1
    Private Sub WebBrowser1_DocumentCompleted(sender As Object, e As WebBrowserDocumentCompletedEventArgs) Handles WebBrowser1.DocumentCompleted
        ListView1.Items.Clear()
        TextBox1.Text = WebBrowser1.Document.Body.InnerText

        '####################---Алгебра---####################'
        Dim Line As Integer
        Dim AlgebraPre1, AlgebraPre2, AlgebraPre3, AlgebraReadyLine As String
        Line = TextBox1.Lines.Count - 1
        For x = 0 To Line Step 1
            If TextBox1.Lines(x) = "Предметы" Then
                AlgebraPre1 = TextBox1.Lines(x + 4)
                AlgebraPre2 = Replace(AlgebraPre1, "+", "")
                AlgebraPre3 = Replace(AlgebraPre2, "H", "")
                AlgebraReadyLine = Replace(AlgebraPre3, " ", "")
            End If
        Next
 
        Dim AlgebraAverageValue As Double
        If Not IsNothing(AlgebraReadyLine) Then AlgebraAverageValue = AlgebraReadyLine.Average(Function(n) Convert.ToInt32(n.ToString))
 
        Dim AlgebraItem As New ListViewItem("Алгебра")
        AlgebraItem.SubItems.Add(AlgebraReadyLine)
        AlgebraItem.SubItems.Add(Math.Round(AlgebraAverageValue, 2))
        ListView1.Items.Add(AlgebraItem)

        '####################---Английский язык---####################'
        Dim EnglishPre1, EnglishPre2, EnglishPre3, EnglishReadyLine As String
        For x = 0 To Line Step 1
            If TextBox1.Lines(x) = "Предметы" Then
                EnglishPre1 = TextBox1.Lines(x + 5)
                EnglishPre2 = Replace(EnglishPre1, "+", "")
                EnglishPre3 = Replace(EnglishPre2, "H", "")
                EnglishReadyLine = Replace(EnglishPre3, " ", "")
                Label2.Text = EnglishReadyLine & " " & Len(EnglishReadyLine)
            End If
        Next
 
        Dim EnglishAverageValue As Double
        If Not IsNothing(EnglishReadyLine) Then EnglishAverageValue = EnglishReadyLine.Average(Function(n) Convert.ToInt32(n.ToString))
 
        Dim EnglishItem As New ListViewItem("Английский")
        EnglishItem.SubItems.Add(EnglishReadyLine)
        EnglishItem.SubItems.Add(Math.Round(EnglishAverageValue, 2))
        ListView1.Items.Add(EnglishItem)
        Label4.Text = AlgebraReadyLine

        '####################---Английский язык---####################'
        Dim BiologyPre1, BiologyPre2, BiologyPre3, BiologyReadyLine As String
        For x = 0 To Line Step 1
            If TextBox1.Lines(x) = "Предметы" Then
                BiologyPre1 = TextBox1.Lines(x + 6)
                BiologyPre2 = Replace(BiologyPre1, "+", "")
                BiologyPre3 = Replace(BiologyPre2, "H", "")
                BiologyReadyLine = Replace(BiologyPre3, " ", "")
                Label2.Text = BiologyReadyLine & " " & Len(BiologyReadyLine)
            End If
        Next
 
        Dim BiologyAverageValue As Double
        If Not IsNothing(BiologyReadyLine) Then BiologyAverageValue = BiologyReadyLine.Average(Function(n) Convert.ToInt32(n.ToString))
 
        Dim BiologyItem As New ListViewItem("Биология")
        BiologyItem.SubItems.Add(BiologyReadyLine)
        BiologyItem.SubItems.Add(Math.Round(BiologyAverageValue, 2))
        ListView1.Items.Add(BiologyItem)
        Label4.Text = AlgebraReadyLine
    End Sub
 
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        WebBrowser1.ScriptErrorsSuppressed = True
        WebBrowser1.Navigate(adress.Text)
    End Sub
 
    Private Sub WebBrowser1_ProgressChanged(sender As Object, e As WebBrowserProgressChangedEventArgs) Handles WebBrowser1.ProgressChanged
        Try
            ProgressBar1.Value = CType((e.CurrentProgress / e.MaximumProgress * 100), Integer)
        Catch Ex As Exception
        End Try
        If ProgressBar1.Value = 100 Then
            Label3.Text = "Успешно!"
        End If
    End Sub
 
    Private Sub NotifyIcon1_MouseDoubleClick(sender As Object, e As MouseEventArgs) Handles NotifyIcon1.MouseDoubleClick
        Me.Show()
        Me.WindowState = FormWindowState.Normal
    End Sub
 
    Private Sub Form1_SizeChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.SizeChanged
        If Me.WindowState = FormWindowState.Minimized Then
            Me.Hide()
        End If
    End Sub
 
    Private Sub Label4_Click(sender As Object, e As EventArgs) Handles Label4.Click
 
    End Sub
End Class