persamaan garis yang melalui titik a (-1,3) dan titik b (-5,7)

(y - y1) / (y2 - y1) = (x - x1) / (x2 - x1)
(y - 3) (7 - 3) = (x + 1) / (- 5 + 1)
(y - 3) / 4 = (x + 1) / - 4
- 4 (y - 3) = 4 (x + 1)
- 4y + 12 = 4x + 4
- 4y - 4x = 4 - 12
- 4y - 4x = - 8
4y + 4x = 8