C. Divide the total distance by the total driving time.
Explanation:
As we are finding average speed across the entire trip, we divide the total distance by the total time taken. This is because speed = distance/time and will give us the average over the whole time.
<h2>In physics, acceleration is defined as the rate of change of the velocity of an object with respect to time. That is A = VF - VI /T;
</h2><h2></h2><h2>Where A = Acceleration
</h2><h2>VF = Final velocity = 20 km
</h2><h2>VI = Initial velocity = 80 km
</h2><h2>T= Time = 0.5 hr
</h2><h2>A = (20 - 80)/ 0.5 = - 60/.5 </h2><h2>A = - 120 Km/ hr^2
</h2><h2></h2><h2>Therefore, the acceleration of the car is -120 km/hr^2.
</h2><h2>
Because the value is negative, the appropriate name that describe it is deceleration.</h2><h2>I Hope this helps</h2>