You drive in a straight line at 20.0 m/s for 12.0 miles, then at 30.0 m/s for another 12.0 miles. (a) Is the car's average speed less than, greater than, or equal to 25.0 m/s? less than 25.0 m/s equal to 25.0 m/s greater than 25.0 m/s (b) Calculate the car's average speed.