A car covers a distance of x,while moving at 54km/1 in 15sec.Find the value of x

Answer 1

is that 54 km/h?

i'll assume so

i will also assume this is constant velocity and not accelerating

you can't compare apples to oranges (or in this case seconds to hours) so you'll need a conversion.

how many seconds in an hour?
60minutes in an hour and 60 seconds per minutes, so 60*60=3600 seconds in one hour

54km/3600s*15s = 0.225km (notice how the seconds cancel out leaving only km)

the answer is also 225meters, which is pretty reasonable if you think about driving. Driving for 15 seconds at around the speed limit gets you about 200 meters. It not ridiculously big or small based on our expectations so that's a good sign.