Speed = Distance/Time

With the wind:

x + y = 2500/225

Against the wind:

x - y = 2500/270

225 = 3h 45m

270 = 4h 30m

x = Plane's speed

y = Wind's speed

225x + 225y = 2500 (1)

270x + 270y = 2500 (2)

Simultaneous equations, I'm sure you can solve it from here.