Let the average speed of the trip there be x km/hour.
Using the formula: Average speed = Total distance / Total time
On the trip there, the distance traveled is the same as the distance traveled on the trip back. Let's call this distance "d".
On the trip there, the total time is 9 hours. On the trip back, the total time is 15 hours.
So we can write two equations:
x = d / 9 (average speed on the trip there)
33 = d / 15 (average speed on the trip back)
We can solve for "d" by multiplying both sides of the second equation by 15:
33 * 15 = d
d = 495 km
Now we can substitute d into the first equation and solve for x:
x = 495 / 9
x = 55 km/hour
Therefore, the average speed of the trip there is 55 km/hour.