Persamaan garis yang melalui titik (2,5) dan tegak lurus 3x – 7y = 12

ay - bx = ax1 - by1
3y - (7x) = (3×2) - (-7×5)
3y + 7x = 6 - (-35)
3y + 7x = 41

3x - 7y = 12
7y = 3x - 12
y = (3/7)x - 12/7

m₁ = 3/7
m₂ (tegak lurus) = -1 × 7/3 = -7/3

Persamaan Garis Lurus Melalui Titik (2, 5)
y - y₁ = m₂(x - x₁)
y - 5 = -7/3 (x - 2)
3y - 15 = -7x + 14
3y = -7x + 29
7x + 3y = 29.