11:25 is correct because 15 minutes pass between 11:15 and 11:30. In those 15 minutes the whale rose 21ft. the Unit rate is 1.4m/ min.
The distance between -80 and -94 is 14 meters. At a rate of 1.4m/min it will take the whale 10 mins to reach -94m. Whale started at -80 at 11:15, and ten mins after that is 11:25