The distance a race car travels is given by the equation, [tex]d=v_{0} t+\frac{1}{2} at^{2}[/tex], where [tex]v_{0}[/tex] is the initial speed of the race car, a is the acceleration and t is the time traveled. Near the beginning of a race, the driver accelerates for 9 seconds at a rate of [tex]4m/s^{2}[/tex]. The driver's initial speed was 75 m/s.

Find the driver's average speed during the acceleration.