Acar moves in a straight line at 16.0 m/s for 10.0 miles, then at 30.0 m/s for another 10.0 miles.

For the first part of the trip:
the car moves at 16 m/sec for 10 miles (which is 16093.44 meters)
velocity = distance / time
time1 = distance / velocity = 16093.44 / 16 = 1005.84 seconds

For the second part of the trip:
the car moves at 30 m/sec for another 10 miles (which is 16093.44 meters)
velocity = distance / time
time2 = distance / velocity = 16093.44 / 30 = 536.448 seconds

For the total trip:
total distance is 20 miles (which is 32186.88 meters)
total time = 1005.84 + 536.448 = 1542.288 seconds
average velocity = total distance / total time = 32186.88 / 1542.288 
                           = 20.869 meters/second

Iwould sure like to answer your question but i honestly just don’t know