Answer:
1. A
2. D
3. D
Explanation:
For one & two: Basically, what you do is you replace the Xs from the answers with all the set of numbers given from the question. You then see after you test the numbers w/ the answers it'll help you find the correct answer.
For three: Using all the numbers starting from zero to the left you use it to solve the problem by utilizing those numbers and replacing it w/ the Xs as explained above to find your answer.