Question

At 7pm last night the temperature was 10°

Answer 1

10 - (-2) = 10 + 2 = 12.....so the temp basically dropped 12 degrees in 12 hrs (because 7 p.m. to 7 a.m. is 12 hrs)

12 degrees / 12 hrs = 1 degree per hr. So the temperature dropped 1 degree per hr