Answer:
C. 72
Explanation:
The whole angle measures 106 degrees as mentioned on top and we know that angle HFG is 34 degrees because it says so in that angle. Just do this: 106-34. The answer is 72. We subtract because we're finding the remaining/missing number in this problem. If you want to check if your answer is correct, you can add 72 and 34.
Another way you could do this is by just adding each option with 34 to see if you get a total of 106.