In a recent grand prix, the winner completed the race with an average speed of 229.8 km/h. what was his speed in miles per hour, meters per second, and feet per second?

Q1)
speed is the rate of change of distance 
the speed is given in km/h
we have to convert to miles/hour
the conversion factor from km to miles is 
1 km = 0.621 miles
since time is hours in both miles/hr and km/hr we need to only convert distance 
229.8 km/h x 0.621 miles/km = 142.7 miles/hr

q2)
next we have to convert km/h into m/s
then we have to convert both distance units and time units
1 km = 1000 m
1 hour = 60 x 60 = 3600 seconds
1 hour is equivalent to 3600 seconds 
within 3600 seconds distance travelled is - 229.8 km
that means within 3600 seconds distance is - 229.8 km x 1000 m/km = 229 800 m

then distance travelled in 1 second - 229 800 m / 3600 s = 63.83 m/s
answer is 63.83 m/s

q3)
we have to then convert to feet per second
again distance units and time units are both different
1 km = 3280.8 feet
1 hour = 3600 seconds
within 1 hour or 3600 s the distance travelled in feet = 229.8 km x 3280.8 feet/km = 753 927.8 feet
then distance travelled in 1 second = 753 927.8 feet/ 3600 s = 209.4 feet/s
answer is 209.4 feet/s

Idont know. if you want an answer you need to give us some context dude.

Are you going to give an example of the plant or?