Program_3-6.py

A_SCORE = 90
B_SCORE = 80
C_SCORE = 70
D_SCORE = 60


score = int(input('Enter your test score: '))


if score >= A_SCORE:
   print ('Your grade is A.')
else:
   if score >= B_SCORE:
      print ('Your grade is B.')
   else:
      if score >= C_SCORE:
         print ('Your grade is C.')
      else:
         if score >= D_SCORE:
            print ('Your grade is D.')
         else:
            print ('Your grade is F.')