a. The speed of the wind is 30 mph
b. The speed of the plane in still air is 450 mph
Let
Since the plane can travel 480 miles per hour with the wind, we have that
V + v = 480 (1)
Also, the plane travels 420 miles per hour against the wind, we have that
V - v = 420 (2)
The speed of the wind is 30 mph
subtracting equations (1) and (2), we have
V + v = 480 (1)
-
V - v = 420 (2)
2v = 60
v = 60/2
v = 30 mph
So, the speed of the wind is 30 mph
The speed of the plane in still air is 450 mph
Substituting v into equation (1), we have
V + v = 480 (1)
V + 30 = 480
V = 480 - 30
V = 450 mph
So, the speed of the plane in still air is 450 mph
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