Let's begin by listing out the information given to us:
Going (with the wind): distance = 495 miles, time = 2.5 hours
Return (without the wind): distance = 340 miles, time = 2.5 hours
velocity = distance / time
v (going) = 495 / 2.5 = 198 mi/hr
v (return) = 340 / 2.5 = 136 mi/hr