Question

Bill and Amy want to ride their bikes from their neighborhood to school which is 14.4 kilometers

Answer 1

First we should convert 14.4 km into meters using the conversion factor 1km = 1000m; thus, 14.4 km = 14,400 m. Next, we should convert all minutes into seconds using the conversion factor 1 min = 60 seconds; thus, 40 mins = 2400 seconds while 20 minutes = 1200 seconds. 
Speed = distance over time
Amy's speed = 14400 m / 2400 sec = 6m/s
Bill's time is 1200 sec + Amy's which is 2400 sec
Bill's speed = 14400m / 3600 sec  = 4 m/s

Therefore, Amy is faster than Bill with 2 m/s difference.