Yeah, these are tough.
When the plane is flying in the same direction as the wind,
the wind helps it cover ground faster.
Plane + Wind = 460 mph
When the plane is flying opposite to the wind, the wind makes it
cover ground slower.
Plane - Wind = 400 mph
================================
OK. So far we have
Plane + Wind = 460 mph
Plane - Wind = 400 mph
Add the two equations, and you get
2 Plane + zero = 860 mph
Divide each side by 2: Plane = 430 mph
Plug that into the first equation: 430mph + Wind = 460 mph
Subtract 430 mph from each side: Wind = 30 mph
