Answer:
to know the summation of angles: (n-2)*180
here (n) represent numbers of sides
12)we have 5 sides (n=5)
(5-2)*180=540
x=540-(105+135+92+87)=121
13)we have 8 sides (n=8)
(8-2)*180=1080
x=1080-(116+158+141+124+136+132+129)=144
I hope it will help
