A train of length 150 metres takes 10 seconds to pass over another train 100 metres long coming from the opposite direction. If the speed of the first train be $30 \mathrm{~km}$ p.h., the speed of the second train is:
(a) $54 \mathrm{~km} / \mathrm{hr}$
(b) $60 \mathrm{~km} / \mathrm{hr}$
(c) $72 \mathrm{~km} / \mathrm{hr}$
(d) $36 \mathrm{~km} / \mathrm{hr}$