The winning time for a 500.0 mile circular race track was 3.33 hours. What was the winning driver's speed? (v = d/t) (write only the answer without the units)

During a race, a sprinter increases his speed from 5.0 m/s to 7.5 m/s over a period of 1.35 s. What is the sprinter's acceleration during this period? [a = (vf - vi) /t] (write only the answer without the units)