By the way the arrow is pointing?
Answer:
see the explanation
Step-by-step explanation:
we have
<em>Felicia</em>

Apply distributive property


Combine like terms

Let
a ----> the missing term with coefficient x in Gregory's expression
b ----> the missing constant term in Gregory's expression
so

equate Gregory's expression to Felicia's expression

so
----->
------> 
so
Gregory's expression is

therefore
The missing terms are 2 and -x
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