Evaluate:

9 - (-12)

A. 3

B. 21

C. - 3

D. - 21

Answer: + 19

Step-by-step explanation: In this problem we are asked to evaluate 9 - (-12).

To subtract these integers, it's important to understand that when we have minus a negative, we can change it to plus a positive.

So 9 - (-12) can be changed to 9 + (+12) or 9 + 12 which gives us a sum of 21.

Therefore, 9 - (-12) = + 21.

Notice that I put the '+' sign in front of the 21. Although this is optional, it's a good idea to do especially when adding and subtracting positives and negatives. All it shows is that our answer is positive.