Respuesta :

calculista
we know that

1 km-------------> 1000 m-----------> 100000 cm
1 min------------> 60 sec

then

10 km is------------> 10*100000------> 1000000 cm
and
54 min is------------> 54*60------------> 3240 sec

hence
[average speed]=distance/time

[average speed]=1000000 cm/3240 sec------------> 308.64 cm/sec

the answer is 
308.64 cm/sec