Question

Yesterday the temperature at noon was 11.4°F by midnight the temperature had decreased by 15.7° what was the temperature at midnight

Answer 1

So you know the temperature you started out with: 11.4°F.

And you know that it decreases 15.7° (Fahrenheit I'm assuming). So all you need to do is subtract 15.7°F from 11.4°F.

11.4 - 15.7 = ?

Answer 2

11.4 - 15.7 = -4.3. The temperature at midnight is -4.3°F.

Hope this helps! Have a great day :)