Nora spends a winter day recording the temperature once every three hours for science class. At 9 am, the temperature was -12.4°F. Between 9am and noon, the temperature increased by 7.6°F. Between noon and 3pm, the temperature went up 13.1°F. Between 3pm and 6pm, the temperature dropped 1.2°F. What was the temperature at 6pm?