Since dolphins cannot breathe underwater, they must reach the surface for air. The time dolphins can stay under the water surface depends on how deep they go and what kind of activities they engage in. To learn more about dolphins, scientists attached a bio-logging sensor to the back of a dolphin and, based on the data collected, they created an equation to model the path of a dolphin's staying underwater: d(t) = 5t - 20t where t is the time in minutes. How long does that particular dolphin stay underwater? Your Answer: Answer units