005 (part 1 of 2) 10.0 points
A runner is jogging in a straight line at asteady v, 4.1 km/hr. When the runner is L= 7.1 km from the finish line, a bird begins
flying straight from the runner to the finish line at = 12.3 km/hr (3 times as fast as the runner). When the bird reaches the finish line, it turns around and flies directly back to the runner.