a b c d

b

Let the distance covered by the ray after reflection from a surface be $d$. From the first law of reflection and alternate angle property, all the angles shown in the figure are equal to $30^o$. From the figure,  $tan 30^o = \frac{d}{0.2}\times \frac{1}{\sqrt 3}$      $ d = \frac{2}{10\sqrt 3} m $​   The ray will not undergo reflection after it emerges out of the arrangement, i.e., after the ray covers $2\sqrt 3$ m. Therefore the maximum number of reflections that occur =$\frac{2\sqrt 3}{2}{10\sqrt 3} = 30$