input: def solve_linear_equation_system(a: float, b: float, c: float) -> tuple:
      """Solves a linear equation system of the form ax + by = c.
      Returns the values of x and y as a tuple.
      
      >>> solve_linear_equation_system(2, 1, 4)
      (2.0, 2.0)
      """
output:     if a == 0 and b == 0:
          raise ValueError("The system has no unique solution.")
      elif a == 0:
          y = c / b
          return (0.0, y)
      elif b == 0:
          x = c / a
          return (x, 0.0)
      else:
          x = c / a
          y = 0.0
          return (x, y)