Answer:
13. 360 14. 1080 15. x=53 16. x=135
Step-by-step explanation:
Equation: (n-2)*180
For 13. all angles in a a quadrilateral add up to 360
For 14. 8 sides-2=6. 180*6=1080 degrees
For 15. 15+155+137=307. 360-307=53. x=53 degrees
For 16. 6 sides-2=4. 4*180=720. 90*2=180. 720-180=540. 540/4=135.
x=135