input: from typing import Tuple
  
  def linear_eq(a: int, b: int, c: int, x: float, y: float) -> float:
      """ Calculate the residual of a linear equation ax + by = c.
      >>> linear_eq(3, 5, 7, 2, 1)
      0.0
      >>> linear_eq(3, 5, 7, 1, 1)
      -1.0
      """
      return a*x + b*y - c
output:     return abs(a*x + b*y - c)