Verified answer

first find out how much the car moves in one second...if it moves 90 km in 3600 secs, that is the same as

90,000 m in 3600 s = 25 m/s

in half a second the car moves 12.5 m

Or you could figure that the car moves 0.025 KM in 1 second, multply that by .5 and get .0125Km.

90000m in 3600 seconds

or 90000/3600 m in 1 second

or 90000/7200 m in 0.5 second =12.5 m in 0.5 second