Answer:
X=8
Explanation:
Since a triangle equals 180°, all the sides added together need to equal 180.
first, add together what you know (71+45=116)
Then, subtract 180 by 116 to get 64.
Now, divide 64 by 8 to get 8
To check your work, simply plug in '8' for 'x' and the answer should be 180
I hope this can help you!