Hitunglah nilai b, jika garis yang menghubungkan titik (4b, 5) dan (2b, 8) bergradien -3

m = -3
y2-y1 / x2-x1 = -3
8-5 / 2b-4b = -3
3/(-2b) = -3
3 = (-3).(-2b)
3 = 6b
b = 3:6
b = 1/2

y¹ = 5 x¹ = 4b
y² = 8 x² = 2b

y² - y¹
_____
x² - x¹

8 - 5
______ = -3
2b - 4b

3
__ = -3
-2b

b = - 3/3
-2b = -1
b = ½