If you have seen this problem before and understand it please do not answer.

So a car is making a 2 mile trip, one mile is up hill and one mile is downhill. On the way up the hill the car averages 30 miles per hour. The driver wants to maintain an average of 60 miles per hour for the entire 2 mile trip. How fast must the driver go down the hill for the second mile to average 60 miles per hour for the trip.

Situation in detail:

The driver has gone one mile so he is at the top of a hill with one mile remaining on his trip.

The driver has averaged 30 miles per hour for the first mile.

He has one mile to go.

Total trip lenght will be 2 miles.

He wants to average 60mph for the 2 miles.

How fast (average) must he go for the remaining mile to average 60mph for the entire 2 mile trip?