Answer: 20 mph due East from Austin
Step-by-step explanation:
The relative speed of A with respect to B is given by:

It is given that average speed of jet airplane travelling west from Texas to Miami is 600 mph.

The speed of the airplane as measured by the observer on the ground:

This is the relative speed of the airplane with respect to wind measured by the observer on the ground.
We need to find the speed of the wind:


As the relative speed is slower, it means the wind is blowing in the opposite direction.
Thus, the speed and direction of blowing wind is 20 mph due East from Austin