# Problem of the Week Problem D Layover Between the Trips

A plane travels from Calgary, AB to Grande Prairie, AB. The total flight time, including takeoff and landing, is $$1$$ hour and $$40$$ minutes. The return flight takes the same route and time. The average speed for these two flights is $$500$$ km/h.

After a brief layover in Grande Prairie, the average speed of this entire round trip (including the two flights and the layover in between) becomes $$425$$ km/h. How long was the layover?