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put this solution on YOUR website!420T=480(1.5-T) T BEING THE TIME FOR THE 420 MPH TRIP
SOLVING FOR T WE GET 420T=720-480T OR 900T=720 OR T=720/900 OR T=.8 HOURS
THE 420 MPH TRIP TOOK .8 HOURS. THE DISTANCE THEN IS 420X.8 OR 336 MILES
THE 480 MPH TRIP THE TOOK 1.5-.8 OR .7 HOURS. 480X.7=336 MILES.