Find the equation of the plane with intercept 3 on the y-axis and parallel to ZOX plane.

Clearly, the plane passes through the point $(0,3,0)$.

The direction cosines of the normal to the plane are $< 0,1,0 >$

$\therefore$ The equation of the plane is,

$0(x - 0) + 1 \cdot (y - 3) + 0(z - 0) = 0$
$\Rightarrow$ $y - 3 = 0 \Rightarrow y = 3$