We know that the distance is the same each way and the plane speed is 150 mph each way. Furthermore, the equation to calculate speed: speed = (distance/time), or v = d/t. Rearranging the equation: d = (v x t)
Let d1 = distance with the wind and let d2 = distance against the wind. Therefor, d1 = d2.
Let t1 = time with the wind and t2 = time against the wind.
Let v1 = total speed with the wind. Total speed is the sum of the plane speed and wind speed: v1 = (vp + vw).
Let v2 = total speed against the wind. Total speed is the difference between plane speed and wind speed: v2 = (vp - vw). Now,
d1 = d2 substituting d with (v x t) since d = (v x t)
(v1 x t1) = (v2 x t2) substituting for each variable v1, t1, v2, t2
(vp + vw)2 = (vp - vw)3 substituting vp with 150
(150 + vw)2 = (150 -vw)3 multiply each side out
300 + 2vw = 450 - 3vw solve algebraically
5vw = 150 solve for vw
vw = 30
The wind speed, vw, is 30 mph.