Answer:
The correct answer is -21 degrees.
Step-by-step explanation:
We know that the original temperature was -12 degrees. If the temperature drops another 9 degrees, this means that it is getting colder or the temperature is getting lower; this lets us know that we should subtract 9 from the original temperature. This is modeled below:
-12 - 9
Now, we simply have to perform the subtraction to get:
-21 degrees
Hope this helps!