Final answer:
After decreasing the temperature by 15 degrees from the initial 8.5 degrees Fahrenheit, the temperature at 11:00 am is -6.5 degrees Fahrenheit.
Step-by-step explanation:
The question asks for the temperature at 11:00 am after a decrease of 15 degrees Fahrenheit from an initial temperature of 8.5 degrees Fahrenheit at 7:00 am. To find the new temperature, subtract the decrease from the initial temperature:
8.5°F - 15°F = -6.5°F
Therefore, the temperature at 11:00 am is -6.5 degrees Fahrenheit.