One cold night the temperature was 0 degrees at 8 p.m. The temperature dropped at a constant rate from 8 p.m. to midnight. At midnight the temperature was −16.8 degrees.
-4.2 degrees. What you would do is from 8-12 (midnight) is 4 hours. So it dropped -16.8 degrees in those 4 hours so -16.8 / 4 is -4.2 degrees. So it dropped -4.2 degrees every hour but it was also -4.2 degrees at 9:00 p.m.
