Answer:

Step-by-step explanation:
As we know that the distance moved by the plane is 1000 miles
So here we know that plane speed is 200 mph in first and last hour of the flight
So we will have


now we know that the remaining distance which it will cover with 400 mph speed is given as

so time taken by it to cover that distance is

so the plane will reach the position of Erehwon at time

