Final answer:
The temperature in Petosky was 24.6°F colder compared to Bay City.
Step-by-step explanation:
To find out how many degrees colder it was in Petosky compared to Bay City, we need to subtract the temperature in Bay City from the temperature in Petosky.
Temperature in Petosky = -13.7°F
Temperature in Bay City = 10.9°F
To find the difference, we subtract the temperature in Bay City from the temperature in Petosky:
-13.7°F - 10.9°F = -24.6°F
Therefore, it was 24.6°F colder in Petosky compared to Bay City.