Not very good with this stuff, needed

1k = 1000m, so we divide 13.5m/s by 1000 and it is 0.0135. Then 1h = 3600s, so we multiply 0.0135km for 3600 and it gives 48.6.

Step-by-step explanation:

We just adjust the measures dividing the meters by the kilometers and multiplying the seconds for the hour. I know that 1h = 3600 seconds so the velocity in one second is 3600 major in an hour, of course dividing the meters by the kilometer value 1000 to balance the operation.