Well, to find the answer to this problem you have to change the -15 to a positive (+15) and add the two numbers together. And, 15 + 68 = +83 degrees.
So, your answer is: A. +83 degrees.
It's really easy because all your doing is changing the -15 to a positive 15 and adding the two numbers together to get your answer.
Hope I helped!
- Debbie