Answer:
The speed of the wind is 3.5 miles per hour.
Solution:
Let x be the speed of the wind
The total time of the trip =

From the Question we know the total time = 1 hr 20 minutes +2 hrs 30 minutes = 3 hrs 50 minutes.
We transform the time in hours and solve the equation:

The equation needed to solve the problem is:

Evaluate to find the value of x.

The speed of wind in positive number so the solution is x = 3.5 miles per hours.