A col front hit Hartford, Connecticut. The temperature dropped by 6 degrees every hour from 4:00 to 9:00 AM. If at 4:00 AM it was 9 degrees, what was the temperature at 9:00 AM?
Dropping 6 degrees per hour, the temperature drops 5×6 = 30 degrees in 5 hours. Starting at 9 degrees and dropping 30, the temperature becomes -21 degrees at 9 am.
