On a road trip, a driver achieved an average speed of (48.0+a) km/h for the first 86.0 km and an average speed of (43.0-b) km/h for the remaining 54.0 km. what was her average speed (in km/h) for the entire trip? round your final answer to three significant figures.

45.94 km/h

Explanation:

Let the average speed be 48km/h for the first 86 km and 43 km/h for the remaining 54 km. We can calculate the time it takes to travel each of the segment:

For the first 86 km segment:

For the remaining 54 km segment:

So the total times it takes is

And the total distance she travels:

The average speed for the entire trip would be total distance divided by total time: