input: 
  from typing import Tuple
  
  def objective_function(coeff_a: int, coeff_b: int, const_c: int, x: int, y: int) -> int:
      """ Calculate the objective function for a given linear equation ax + by = c.
      >>> objective_function(3, 5, 7, 1, 1)
      1
      >>> objective_function(3, 5, 7, 2, 2)
      3
      """
      return coeff_a * x + coeff_b * y - const_c
  
output:     return abs(coeff_a * x + coeff_b * y - const_c)