Assignament Grader issue

[vargf]

Hi i'm new in programming, I working in a Assignament Grader,but I face a problem all the result
I want to get Letters insted of numbers for example:
beetwen 100-99=A, 80-89=B, 70-79=C, 60-69=D, 0-59=F.

here is my code and works greate but again I want to display letters istead of numbers.

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
'This is NumericUpDown to get score 0 to 100 maximun.

'This is the RadioBottoms section to select the a average and the time liness
'moreover,
'Instead of using FinalGrade = FinalGrade + 0
'I use a short cut to save space
If (none.Checked) Then
FinalGrade += 0
End If
If (Average.Checked) Then
FinalGrade += 3
End If
If (AboveAverage.Checked) Then
FinalGrade += 5
End If
If (OnTime.Checked) Then
FinalGrade += 0
End If
If (OneToTwoDaysLate.Checked) Then
FinalGrade -= 3
End If
If (TwoPlusLate.Checked) Then
FinalGrade -= 5
End If

'This is the output result
'txtFinalGrade.Text = FinalGrade
txtFinalGrade.Text = FinalGrade

 

[JohnH]

Select Case FinalGrade
Case 0 To 59
  txtFinalGrade.Text = "F"
Case 60 To 69
  txtFinalGrade.Text = "D"
Case 70 To 79
  txtFinalGrade.Text = "C"
Case 80 To 89
  txtFinalGrade.Text = "B"
Case 90 To 100
  txtFinalGrade.Text = "A"
End Select