input: from typing import Tuple
  
  
  def solve_linear_equation_system(a: float, b: float, c: float) -> Tuple[float, float]:
      """Solve a linear equation system of the form: ax + by = c.
      >>> solve_linear_equation_system(2, 1, 4)
      (2.0, 0.0)
      """
      x = (c - b) / a
      y = (c - a * x) / b
      return x, y
output:     if a == 0 and b == 0:
          raise ValueError("The system has no unique solution.")
      if a == 0:
          y = c / b
          return 0.0, y
      if b == 0:
          x = c / a
          return x, 0.0