A scuba diver dove down from a surface of the ocean to an elevation of -59 9/10 feet to a rate of -16 feet per minute. After spending 11.75 minutes at that elevation the diver ascended to an elevation of -28 9/10 feet . The total time for the dive so far was 18 1/8 minutes. What was the rate of change in the divers elevation during ascent? Round your answer to the nearest hundredth. The rate changed of the divers elevation was ft/min