A train 100 metres long takes $3 \frac{3}{5}$ seconds to cross a man walking at the rate of $6 \mathrm{~km} / \mathrm{hr}$ in a direction opposite to that of the train. Find the speed of the train.
(a) $76 \mathrm{~km} / \mathrm{hr}$
(b) $94 \mathrm{~km} / \mathrm{hr}$
(c) $86 \mathrm{~km} / \mathrm{hr}$
(d) None of these