Answer:
11. x= 117 and y =57
12. 9
13. 900 degrees
Explanation:
11. Y can be found using supplementary angles. 123+y = 180 since they form a straight line. This means y=57. The inside of a quadrilateral is equal to 360 degrees. This means 117+69+57 +x=360. Then 243+x=360 and x= 117.
12. The exterior angles of a polygon with n sides is 360/n. Since we don't know n but we do know the angle is 40 degrees, we write 360/n=40. Solve for n.
360/n=40
360=40n
360/40=n
n= 9
13. This figure is a regular sides polygon. It has 7 sides and therefore 900 degrees.