Answer:
1°C
Explanation:
The inicial temperature at 09:00 was -3°C.
The changes in temperature in each of the six hours were:
first hour: -2°C
secondhour: +3°C
third hour: +2°C
fourth hour: -1°C
fifth hour: +4°C
sixth hour: -2°C
So, the temperature at 15:00 is the sum of the inicial temperature and all of these changes:
Temperature at 15:00 = -3°C -2°C +3°C +2°C -1°C +4°C -2°C = 1°C