What latitude was the person flying along on September 21 at sunset?

[B Robison]

Homework Statement

A person flying east on September 21 at sunrise hears the time is 2:00PM Greenwich Time. Flying hour after hour at 105 MPH over nothing but water see the the sun set in only ten hours since sunrise. Along what line of latitude have they been flying.

Homework Equations

The Attempt at a Solution

either 60 degrees N; 20 degrees N; 20 degrees So. or 60 degrees So.

 

[Borek]

While I am not sure how to solve (not without drawing a sketch on paper at least) I don't think there can be 4 different solutions. Two at best (and probably one is impossible because of flying over water all the time). Think what distance has been covered in 10 hours, and what part of the full circle it was if the day lasted 10 hours instead of its expected duration.