How do i change this code to a case statement and not a if? (this is delphi 7 code)?

[Brendan Louw]

if rFinal >= 80
then edtFinal.Text := 'A'
else if rFinal >= 70
then edtFinal.Text := 'B'
else if rFinal >=60
then edtFinal.Text := 'C'
else iF rFinal >= 50
then edtFinal.Text := 'D'
else if rFinal >= 40
then edtFinal.Text := 'E'
else if rFinal >= 0
then edtFinal.Text := 'F'