input: 
  def linear_eq(a: int, b: int, c: int, x: int, y: int) -> int:
      """
      Calculate the objective function of a linear equation ax + by = c.
      Returns the overall function ax + by - c.
      >>> linear_eq(3, 5, 7, 1, 1)
      1
      >>> linear_eq(1, 2, 3, 2, 3)
      5
      """
      return a*x + b*y - c
  
output:     return a*x + b*y - c