Hi
train is 40 miles per hour faster than the cars
Let x and (x+40mph)represent the speed of the car and train respectively
Question states*** Time is the same. t = D/r
| Cross Multiplying
280x = 140(x+40)
140x = 5600
x = 40mph, the average speed of the car's. train's average speed is 80mph
CHECKING our Answer***
140mi/40mph = 280mi/80mph = 3.5 hr