Parakeets On Parade

     Early every morning I and my family are treated to a unique "alarm clock", the chatter of a flock of parakeets flying over our neighborhood. They are en route from their nesting grounds to their feeding grounds where they spend the day eating, of course. In the evening around sunset this is repeated, as the birds head back to their nests to spend the night.

     One morning as they left their nests, they flew with a gentle tail wind of 5 mph assisting them. That evening, for their return flight they faced a stronger breeze of 15 mph. Assuming that their round trip distance was 30 miles, their round trip flying time was 2 hours, and that their own flying speed was constant in both instances, find their normal flying speed (in still air).