A truck covers 40 km with an average speed of 80 km/h. It then travels another 40 km with a speed of 40 km/h. What was the time taken to
complete the entire journey?

53.33 km/hr

Step-by-step explanation:

The total distance covered by car is 80 KM(40+40).

Now their are two cases:

Case 1) Distance covered 40km, speed 80km/h. Now we all know speed=Distance/ time

So Time taken is 0.5 hour.

Case 2) Now again distance covered is 40 km but speed is 40Km/h

So time taken is 1 hr

Now total distance traveled is 80KM. Total time taken is 1.5 hrs (0.5+1)

Average speed =Total Distance/Total Time

Average Speed = 80/1.5

Which is equal to 53.33km/h

the first one is x^2+2x+2

the second one is x^2+4

the last one is x^2-4x+8