Jeremiah spends a winter day recording the temperature once every three hours for science class. At 9 am, the temperature was -3.6°F. Between 9am and noon, the temperature rose 15.4°F. Between noon and 3pm, the temperature went down 15.5°F. Between 3pm and 6pm, the temperature went down 9.3°F. What was the temperature at 6pm?