Official solution
Let the equation of the plane is a (x - 1) + b(y - 2) + c(z - 3) = 0
Y-axis lies on it.
D.R.'s of y-axis are 0, 1, 0
\[ \therefore \] 0.a + 1.b + 0.c = 0 \[ \Rightarrow \] b = 0
\[ \therefore \] Equation of plane is a(x - 1) + c(z - 3) = 0
x = 0, z = 0 also satisfy it -a -3c = 0 \[ \Rightarrow \] a = -3c
-3c (x - 1) + c (z - 3) = 0
-3 + 3 + z - 3 = 0
3x - z = 0