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a scuba diver dove from the surface of the ocean to an elevation of −99 9/10 feet at a rate of −23.5 feet per minute. after spending 14.5 minutes at that elevation, the diver ascended to an elevation of −38 9/10 feet. the total time for the dive so far was 21 1/8 minutes. what was the rate of change in the diver's elevation during the ascent? round your answer to the nearest hundredth.

the rate of change of the diver's elevation was ft/min.