Answer:
<em>is your answer.</em>
Step-by-step explanation:

B
if it is not correct sory
A. Definition of Congruence
Answer:
the answer is c mathematical way
Answer: x=14
Explanation: the angle needs to equal the other angle, which is 63. To figure this out, we subtract 21 from 63. We get 42. 42 divided by 3 is 14. We are basically doing the equation in reverse.