Since, $PQ$ is perpendicular to the plane $2 x-3 y+4 z=29 .$
Hence, DR's of $P Q$ will be $<\,2,-3,4\,>$
Equation of line $PQ$ will be
$\frac{x-0}{2} =\frac{y-0}{-3} $
$=\frac{z-0}{4}=\lambda$ (say)
Coordinates of $Q$ will be $(2 \lambda,-3 \lambda, 4 \lambda)$
$\because Q$ lies on plane, so $4 \lambda+9 \lambda+16 \lambda=29$
$\Rightarrow \, \lambda=1$
$\therefore $ Coordinates of $Q$ are $(2,-3,4)$
