Scuba diver dove from the surface of the ocean to an elevation of -89 9/10 feet at a rate of -24 ft./min. after spending 11 minutes at that elevation the diver ascended to an elevation of -18 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 the ascent round your answer to the nearest hundredth