Let x= speed in mph on the return flight.510/x=time distace/rate=timeNow to figure time for the first half of the flight. distance =510 miles, rate was given as 255 mph. time=510/255 = 2 hours for the first half. Time for the round triip is given as 3.9h. Subtract 2 and you find the time for the return trip.3.9-2=1.9. Since this is less time for the first part you can answer part of problem now. The wind was a tail wind.Now to the equation 510/x=1.9.1.9x=510x=268.421 mph