You can use any distance unit you want. But whatever unit you choose,
you'll need to EITHER change the 15 m/s and the 20 mins to be consistent
before you multiply them, OR change the answer to your chosen unit after
you multiply.
Examples:
#1). I choose the unit of meters.
(20 mins) x (60 sec/min) = 1200 sec
(15 m/s) x (1200 sec) = (15 x 1200) m-sec/sec = 18,000 meters .
= 18.0 kilometers
#2). I choose the unit of feet.
(15 mtr/s) x (3.28 ft/mtr) = 49.2 ft/sec
(49.2 ft/sec) x (20 min) x (60 sec/min)
= 59,055 feet x (1 mile / 5,280 ft)
= 11.2 miles
