avgGrade :: (Fractional a, Ord a) => a -> Char
avgGrade x 
  | y >= 0.9    = 'A'
  | y >= 0.8    = 'B'
  | y >= 0.7    = 'C'
  | y >= 0.59   = 'D'
  | otherwise   = 'F'
  where y = x / 100
avgGrade :: (Fractional a, Ord a) => a -> Char
avgGrade x 
  | y >= 0.9    = 'A'
  | y >= 0.8    = 'B'
  | y >= 0.7    = 'C'
  | y >= 0.59   = 'D'
  | otherwise   = 'F'
  where y = x / 100
avgGrade x 
  | y >= 0.9    = 'A'
  | y >= 0.8    = 'B'
  | y >= 0.7    = 'C'
  | y >= 0.59   = 'D'
  | otherwise   = 'F'
  where y = x / 100