At 4:00 PM, the temperature started rising 2°C per hour until it reached –19°C at 7:00 PM. What was the temperature at 4:00 PM?

To solve this problem, we need to understand that the temperature was rising, or increasing, by 2°C every hour from 4:00 PM to 7:00 PM.

1. First, we need to find out how many hours passed from 4:00 PM to 7:00 PM. This is 3 hours.

2. Since the temperature was rising 2°C per hour, over 3 hours it would have risen by 2°C * 3 hours = 6°C.

3. We know that the temperature at 7:00 PM was -19°C. Since the temperature rose to this, it must have been lower 3 hours earlier.

4. Therefore, to find the temperature at 4:00 PM, we subtract the amount the temperature rose (6°C) from the final temperature (-19°C).

So, -19°C - 6°C = -25°C.

Therefore, the temperature at 4:00 PM was -25°C.