Answer:
21km
15min
1.4km/min
Step-by-step explanation:
Distance of car at 8:15am = 53819km
Distance of car at 8:30am = 53840km
Unknown:
Distance covered by car = ?
Time taken = ?
Speed = ?
Solution:
This is a motion problem and it is easy to solve;
Distance is the length of path covered by a moving body
Time is the duration of the motion
Speed is the rate of change of distance with time:
Speed =

Distance covered = 53840 - 53819 = 21km
Time taken = 8:30 - 8:15 = 15minutes
Speed =
= 1.4km/min