tolong jawab nomor 40

P(a, 3)
x1 = a
y1 = 3

Q(3, 5a)
x2 = 3
y2 = 5a

m = (y2 - y1) / (x2 - x1)
7 = (5a - 3) / (3 - a)
7(3 - a) = 5a - 3
21 - 7a = 5a - 3
-7a - 5a = -3 - 21
-12a = -24
a = (-24) / (-12)
a = 2

Jawaban B