Answer
$ 7.94\;\rm \mu m$
Work Step by Step
In a diffraction grating experiment, we know that the bright fringes are given by
$$d\sin\theta_m=m\lambda$$
And at $m=1$,
$$d\sin\theta_1=\lambda$$
So,
$$d=\dfrac{\lambda}{\sin\theta_1}\tag 1$$
Now we need to find $\theta_1$, as we see in the figure below, [see the yellosih right-triangle below],
$$\theta_1=\tan^{-1}\left[ \dfrac{16}{200} \right]=\bf 4.57^\circ$$
Plugging the known into (1);
$$d=\dfrac{633\times 10^{-9}}{\sin4.57^\circ}=\bf 7.94\times 10^{-6}\;\rm m$$
$$d=\color{red}{\bf 7.94}\;\rm \mu m$$
