Answer:
The temperature at noon was -10ºF + 15º = 5ºF.
Then, from noon to 7:00 pm, there were 7 hours, during which the temperature dropped 25º. Therefore, the temperature at 7:00 pm was:
5ºF - 25º = -20ºF.
So, the temperature at 7:00 pm was -20ºF.
Explanation: