I WILL MARK BRAINLIEST IF THIS IS ANSWERED IN LESS THAN 30 MIN.
When Erik went to bed one winter night in northern Minnesota, the temperature was -2°F. By the time he got up the next morning, the temperature had dropped to -17°F. Assuming the temperature dropped steadily through the night, what was the temperature in the middle of the night?

-19°F
-9.5°F
-15°F
-8.5°F