input: def solve_linear_equation_system(a: int, b: int, c: int) -> tuple:
      """ Solve a linear equation system of the form ax + by = c.
      >>> solve_linear_equation_system(2, 1, 4)
      (2.0, 2.0)
      """
output:     if a == 0 and b == 0:
          if c == 0:
              return (float('inf'), float('inf'))
          else:
              return None
      elif a == 0:
          return (float('inf'), c / b)
      elif b == 0:
          return (c / a, float('inf'))
      else:
          return (c / a, (c - a * (c / a)) / b)