On January 22 in 1943, the town of Spearfish, South Dakota, set the record for the world’s fastest temperature change. At 7:30 a.m., the temperature was −4°F. By 7:32 a.m., the temperature was 45°F. By 9:00 a.m. the same day, the temperature was 54°F. By 9:27 a.m., the temperature was −4°F. What is the difference between the temperature at 7:30 and the temperature at 9:27? Make sure to show whether the change was positive or negative.