Answer:
-15°
Explanation:
We know that at 7 pm it started at -6°, and that every 2 hours until 2 am, it dropped by 2 degrees.
From that we can form this expression:
-6-2x, with x being the number of hours it dropped.
From 7 pm to 2 am is 7 hours, therefore -6-2(7) = -20°
From 2 am until 7 am, it began raising 1 degree per hour.
We can write that as:
-20 + x, with x being the number of hours it went up.
From 2 am to 7 am is 5 hours:
-20 + 5 = -15°
Therefore, the temperature at 7 am is -15°.