Step-by-step explanation:
Draw lines from one vertex to the other vertices, splitting the polygon into triangles.  If the polygon has n sides, there will be n−2 triangles.  Each triangle's angles add up to 180°.  So the sum of all the interior angles is:
S = (n−2) 180°
 
        
             
        
        
        
Answer:
9 and -5
Step-by-step explanation:
9*-5=-45
9+-5=4
 
        
                    
             
        
        
        
Given that original lenght of the board before cut  meter
meter
Lenght of the board that is left after cutting from the original piece by Hernan  meter
meter
Now we have to find the lenght of the piece which is cut.
To find that we just need to subtract smaller piece from larger piece
Required Length  meter
meter
Required Length  meter
meter
Required Length meter
meter
reduce the fraction
Required Length  meter
meter
Hence final answer is  meter.
 meter.
 
        
                    
             
        
        
        
Answer:

Step-by-step explanation:
The reciprocal of 5: 
The negative reciprocal of 5: 
 
        
             
        
        
        
Answer to the first question: 7/10ths of a mile
Explaination: When adding fractions, you need to have a common denominator. Since dividing 3/10 by 2 to get a denominator of 5 makes 3 a decimal, it's easier to multiply 2/5 by 2 to get a denominator of 10. You do the same to the top that you do to the bottom:  . From there, just add 4/10 and 3/10 to get the answer: 7/10ths of a mile.
. From there, just add 4/10 and 3/10 to get the answer: 7/10ths of a mile.
Answer to the second question: Daniel read three (3/10) more books
Explaination: Since you can't evenly multiply 5 or 2 to get the opposite number, it's easier to multiply to the lowest common multiple. The easiest way to find that is to multiply both denominators (5*2=10). You'll have to multiply the numerator by the same amount you multipled the denominator by. For Daniel, that would mean:  . For Edgar, that would mean:
. For Edgar, that would mean:  . So, Daniel read 3 more books than Edgar.
. So, Daniel read 3 more books than Edgar.
Answer to the third question: 2/4 mile (or 1/2 a mile) 
Explaination: 2/8 can be simplified, by dividing the top and bottom by 2, resulting in 1/4. Since both fractions have the same denominator (/4), you can add them to get 2/4ths. This can be simplified further to half (1/2) a mile.