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 yards per minute. We calculate as follows:
12 / 60 minutes = 0.2 miles/minute
0.2 × 5280 ft = 1056 ft/minute
1056 / 3 ft = 352 yds/minute
4.4 x 60 = 264 ft/minute
264 / 3 = 88 yds/minute
352 - 88 = 264 yds/minute faster than the boy