Guadalupe spends a winter day recording the temperature once every three hours for science class. At 9 am, the temperature was -5.4°F. Between 9am and noon, the temperature rose 9.4°F. Between noon and 3pm, the temperature went down 13.6°F. Between 3pm and 6pm, the temperature went down 16.9°F. What was the temperature at 6pm?