To compare the speed for the both of them, it would be helpful to convert the units to the same units in this case to units of meters per minute. We calculate as follows:
27 / 60 minutes = 0.45 km/minute
0.45 × 1000 = 450 m/minute
14 x 60 = 840 dm/minute
840 / 10 = 84 m/minute
450 - 84 = 366 m/minute faster than the girl
