Speed is given by the distance traveled divided by the time spent.
The net speed with which the plane traveled against the wind is given by
while the speed with which the plane travelled in the return trip is given by
Let the speed of the plane be v and the speed of the wind be w, then when the plane was traveling against the sun, we have, v - w = 168.57 and when the plane is travelling in the direction of the wind, we have, v + w = 236.
Subtracting the first equation from the second equation, we have: 2w = 236 - 168.57 = 67.43
Thus, w = 67.43 / 2 = 33.715
Therefore, the speed of the wind is approximately 33.7 mi/hr.