Alright, so I think I know where to go with this question. I'll lay out the information so it's easier to follow.
0 Hours - 10 degrees
1 Hour - 6 degrees
2 Hours - 2 degrees
3 Hours - -2 degrees
4 Hours - -6 degrees
5 Hours - -10 degrees
6 Hours - -2 degrees
7 Hours - 6 degrees
8 Hours - 14 degrees
9 Hours - 22 degrees
A = 2 Degrees Celsius
B = -10 Degrees Celsius
C = 22 Degrees Celsius
Hope this helps!