The definition is pretty simple:

So, we only have to sum the expressions:

 
        
             
        
        
        
Answer:
choice 1) 2x + 40 = 180
Step-by-step explanation:
(x + 10) + (x + 30) = 180
2x+ 40 = 180
 
        
                    
             
        
        
        
Answer:
26.2 units 
Step-by-step explanation:
We are given the points/vertices 
A(6, 3), 
B(6, - 2) , and 
C(- 4, 3)
Step two 
Let us find the distances between the given points/vertices
A-B =A(6, 3) to B(6,-2)
d=√((x2-x1)²+(y2-y1)²)
Substitute 
d=√((6-6)²+(-2-3)²)
d=√(-2-3)²)
d=√(-5)²)
d=5 units
B-C=B(6, - 2) to C(-4, 3)
d=√((x2-x1)²+(y2-y1)²)
Substitute 
d=√((-4-6)²+(3+2)²)
d=√(-10)²+(5)²)
d=√100+25
d=√125
d=11.2 units 
C-A=C(-4, 3) to A(6, 3)
d=√((x2-x1)²+(y2-y1)²)
Substitute 
d=√((6+4)²+(3-3)²)
d=√(10)²
d=√100
d=10 units 
Hence the perimeter is 5+11.2+10
P=26.2 units