Persamaan garis lurus melalui titik -9,4 dan 3,12

PGL

(y – y₁)/(y₂ – y₁) = (x – x₁)/(x₂ – x₁)

(y – 4)/(12 – 4) = (x + 9)/(3 + 9)

12(y – 4) = 8(x + 9)

12y – 48 = 8x + 72

8x – 12y + 120 = 0

2x – 3y + 30 = 0