Answer:
Step-by-step explanation:
<u><em>
Options are:
</em></u>
- <em>2 feet
</em>
 - <em>3 feet
</em>
 - <em>9 feet
</em>
 - <em>15 feet
</em>
 - <em>19 feet
</em>
 - <em>21 feet
</em>
 - <em>30 feet</em>
 
<em>-------------------------------------</em>
Use the triangle inequality theorem: sum of any two side must be greater than the third side by length
- 2 feet     ⇒  no, as 2 + 9 < 12
 - 3 feet     ⇒  no, as 3 + 9 = 12
 - 9 feet     ⇒  yes
 - 15 feet    ⇒  yes
 - 19 feet    ⇒  yes
 - 21 feet    ⇒  no, as 9 + 12 = 21
 - 30 feet  ⇒  no, as 9 + 12 < 30
 
 
        
             
        
        
        
Answer:
64
Step-by-step explanation:
60 + 56 + x = 180
116 + x = 180
x = 180 - 116
x = 64
 
        
                    
             
        
        
        
Answer:

Step-by-step explanation: